Centre for Chronobiology

@article{Schöllhorn2023b,

title = {Seasonal Variation in the Responsiveness of the Melanopsin System to Evening Light: Why We Should Report Season When Collecting Data in Human Sleep and Circadian Studies},

author = {I. Schöllhorn and O. Stefani and C. Blume and C. Cajochen},

url = {https://www.mdpi.com/2624-5175/5/4/44},

doi = {https://doi.org/10.3390/clockssleep5040044},

year  = {2023},

date = {2023-11-01},

urldate = {2023-11-01},

journal = {Clocks & Sleep},

abstract = {Abstract

It is well known that variations in light exposure during the day affect light sensitivity in the evening. More daylight reduces sensitivity, and less daylight increases it. On average days, we spend less time outdoors in winter and receive far less light than in summer. Therefore, it could be relevant when collecting research data on the non-image forming (NIF) effects of light on circadian rhythms and sleep. In fact, studies conducted only in winter may result in more pronounced NIF effects than in summer. Here, we systematically collected information on the extent to which studies on the NIF effects of evening light include information on season and/or light history. We found that more studies were conducted in winter than in summer and that reporting when a study was conducted or measuring individual light history is not currently a standard in sleep and circadian research. In addition, we sought to evaluate seasonal variations in a previously published dataset of 72 participants investigating circadian and sleep effects of evening light exposure in a laboratory protocol where daytime light history was not controlled. In this study, we selectively modulated melanopic irradiance at four different light levels (<90 lx). Here, we aimed to retrospectively evaluate seasonal variations in the responsiveness of the melanopsin system by combining all data sets in an exploratory manner. Our analyses suggest that light sensitivity is indeed reduced in summer compared to winter. Thus, to increase the reproducibility of NIF effects on sleep and circadian measures, we recommend an assessment of the light history and encourage standardization of reporting guidelines on the seasonal distribution of measurements.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Schöllhorn, I; Stefani, O; Lucas, R; Spitschan, M; Slawik, H; Cajochen, C.

Melanopic irradiance defines the impact of evening display light on sleep latency, melatonin and alertness Journal Article

In: Communications Biology, iss. 6, no. 228, 2023.

Lasauskaite, R; Richter, M; Cajochen, C.

Lighting color temperature impacts effort-related cardiovascular response to an auditory short-term memory task Journal Article

In: Journal of Environmental Psychology, 2023.

Stampfli, J. R.; Schrader, B.; di Battista, C.; Häfliger, R.; Schälli, O.; Wichmann, G.; Zumbühl, C.; Blattner, P.; Cajochen, C.; Lazar, R.; Spitschan, M.

The Light-Dosimeter: A new device to help advance research on the non-visual responses to light Journal Article

In: Lighting Research & Technology, 2023.

Brain activity during a working memory task after daily caffeine intake and caffeine withdrawal: a randomized double-blind placebo-controlled trial. Journal Article

Lin, Y. -S.; Weibel, J.; Landolt, H. -P.; Santini, F.; Slawik, H.; Borgwardt, S.; Cajochen, C.; Reichert, C. F.

In: Scientific Reports, vol. 13, iss. 1, no. 1002, 2023.

@article{nokey,

title = {Brain activity during a working memory task after daily caffeine intake and caffeine withdrawal: a  randomized double-blind placebo-controlled trial.},

author = {Y.-S. Lin and J. Weibel and H.-P. Landolt and F. Santini and H. Slawik and S. Borgwardt and C. Cajochen and C. F. Reichert},

doi = {10.1038/s41598-022- 26808-5},

year  = {2023},

date = {2023-01-18},

urldate = {2023-01-18},

journal = {Scientific Reports},

volume = {13},

number = {1002},

issue = {1},

abstract = {Acute caffeine intake has been found to increase working memory (WM)-related brain activity in healthy adults without improving behavioral performances. The impact of daily caffeine intake-a ritual shared by 80% of the population worldwide-and of its discontinuation on working memory and its neural correlates remained unknown. In this double-blind, randomized, crossover study, we examined working memory functions in 20 young healthy non-smokers (age: 26.4 ± 4.0 years; body mass index: 22.7 ± 1.4 kg/m2; and habitual caffeine intake: 474.1 ± 107.5 mg/day) in a 10-day caffeine (150 mg × 3 times/day), a 10-day placebo (3 times/day), and a withdrawal condition (9-day caffeine followed by 1-day placebo). Throughout the 10th day of each condition, participants performed four times a working memory task (N-Back, comprising 3- and 0-back), and task-related blood-oxygen-level-dependent (BOLD) activity was measured in the last session with functional magnetic resonance imaging. Compared to placebo, participants showed a higher error rate and a longer reaction time in 3- against 0-back trials in the caffeine condition; also, in the withdrawal condition we observed a higher error rate compared to placebo. However, task-related BOLD activity, i.e., an increased attention network and decreased default mode network activity in 3- versus 0-back, did not show significant differences among three conditions. Interestingly, irrespective of 3- or 0-back, BOLD activity was reduced in the right hippocampus in the caffeine condition compared to placebo. Adding to the earlier evidence showing increasing cerebral metabolic demands for WM function after acute caffeine intake, our data suggest that such demands might be impeded over daily intake and therefore result in a worse performance. Finally, the reduced hippocampal activity may reflect caffeine-associated hippocampal grey matter plasticity reported in the previous analysis. The findings of this study reveal an adapted neurocognitive response to daily caffeine exposure and highlight the importance of classifying impacts of caffeine on clinical and healthy populations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Acute caffeine intake has been found to increase working memory (WM)-related brain activity in healthy adults without improving behavioral performances. The impact of daily caffeine intake-a ritual shared by 80% of the population worldwide-and of its discontinuation on working memory and its neural correlates remained unknown. In this double-blind, randomized, crossover study, we examined working memory functions in 20 young healthy non-smokers (age: 26.4 ± 4.0 years; body mass index: 22.7 ± 1.4 kg/m2; and habitual caffeine intake: 474.1 ± 107.5 mg/day) in a 10-day caffeine (150 mg × 3 times/day), a 10-day placebo (3 times/day), and a withdrawal condition (9-day caffeine followed by 1-day placebo). Throughout the 10th day of each condition, participants performed four times a working memory task (N-Back, comprising 3- and 0-back), and task-related blood-oxygen-level-dependent (BOLD) activity was measured in the last session with functional magnetic resonance imaging. Compared to placebo, participants showed a higher error rate and a longer reaction time in 3- against 0-back trials in the caffeine condition; also, in the withdrawal condition we observed a higher error rate compared to placebo. However, task-related BOLD activity, i.e., an increased attention network and decreased default mode network activity in 3- versus 0-back, did not show significant differences among three conditions. Interestingly, irrespective of 3- or 0-back, BOLD activity was reduced in the right hippocampus in the caffeine condition compared to placebo. Adding to the earlier evidence showing increasing cerebral metabolic demands for WM function after acute caffeine intake, our data suggest that such demands might be impeded over daily intake and therefore result in a worse performance. Finally, the reduced hippocampal activity may reflect caffeine-associated hippocampal grey matter plasticity reported in the previous analysis. The findings of this study reveal an adapted neurocognitive response to daily caffeine exposure and highlight the importance of classifying impacts of caffeine on clinical and healthy populations.

Münch, M.; Goldbach, R.; Zumstein, N.; Vonmoos, P.; Scartezzini, J. -L.; Wirz-Justice, A.; Cajochen, C.

Preliminary evidence that daily light exposure enhances the antibody response to influenza vaccination in patients with dementia Journal Article

In: Brain, Behavior, & Immunity - Health, vol. 26, pp. 100515, 2022.

Altena, E.; Baglioni, C.; Sanz-Arigita, E.; Cajochen, C.; Riemann, D.

How to deal with sleep problems during heatwaves: practical recommendations from the European Insomnia Network Journal Article

In: Journal of Sleep Research, pp. e13704, 2022.

Garbazza, C.; Hackethal, S.; Migliore, E.; D'Agostino, A.; Serrati, C.; Fanti, V.; Riccardi, S.; Baiardi, S.; Cicolin, A.; Borgwardt, S.; Mondini, S.; Cirignotta, F.; Cajochen, C.; Manconi, M.; study group, “Life-ON”

Influence of chronotype on the incidence and severity of perinatal depression in the "Life-ON" study Journal Article

In: Journal of Affective Disorders, vol. 317, pp. 245-255, 2022.

Blume, C.; Niedernhuber, M.; Spitschan, M.; Slawik, H. C.; Meyer, M. P.; Bekinschtein, T. A.; Cajochen, C.

Melatonin suppression does not automatically alter sleepiness, vigilance, sensory processing, or sleep Journal Article

In: SLEEP, 2022.

@article{Blume2022,

title = {Melatonin suppression does not automatically alter sleepiness, vigilance, sensory processing, or sleep},

author = {C. Blume and M. Niedernhuber and M. Spitschan and H. C. Slawik and M. P. Meyer and T. A. Bekinschtein and C. Cajochen},

doi = {https://doi.org/10.1093/sleep/zsac199},

year  = {2022},

date = {2022-08-23},

journal = {SLEEP},

abstract = {Pre-sleep exposure to short-wavelength light suppresses melatonin and decreases sleepiness with activating effects extending to sleep. This has mainly been attributed to melanopic effects, but mechanistic insights are missing. Thus, we investigated whether two light conditions only differing in the melanopic effects (123 vs. 59 lux melanopic EDI) differentially affect sleep besides melatonin. Additionally, we studied whether the light differentially modulates sensory processing during wakefulness and sleep.

Twenty-nine healthy volunteers (18-30 years, 15 women) were exposed to two metameric light conditions (high- vs. low-melanopic, ≈60 photopic lux) for 1 hour ending 50 min prior to habitual bed time. This was followed by an 8-h sleep opportunity with polysomnography. Objective sleep measurements were complemented by self-report. Salivary melatonin, subjective sleepiness, and behavioural vigilance were sampled at regular intervals. Sensory processing was evaluated during light exposure and sleep on the basis of neural responses related to violations of expectations in an oddball paradigm.

We observed suppression of melatonin by ≈14 % in the high- compared to the low-melanopic condition. However, conditions did not differentially affect sleep, sleep quality, sleepiness, or vigilance. A neural mismatch response was evident during all sleep stages, but not differentially modulated by light. Suppression of melatonin by light targeting the melanopic system does not automatically translate to acutely altered levels of vigilance or sleepiness or to changes in sleep, sleep quality, or basic sensory processing. Given contradicting earlier findings and the retinal anatomy, this may suggest that an interaction between melanopsin and cone-rod signals needs to be considered.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Garbazza, C.; Cirignotta, F.; D'Agostino, A.; Cicolin, A.; Hackethal, S.; Wirz-Justice, A.; Cajochen, C.; Manconi, M.

Sustained remission from perinatal depression after bright light therapy: a pilot randomised, placebo-controlled trial Journal Article

In: Acta Psychiatr Scand, vol. 146, pp. 350–356., 2022.

Chellappa, S. L.; Bromundt, V.; Frey, S.; Schlote, T.; Goldblum, D.; Cajochen, C.

Cross-sectional study of intraocular cataract lens replacement, circadian rest-activity rhythms, and sleep quality in older adults Journal Article

In: Sleep, vol. 45, no. 4, pp. zsac027, 2022.

Benedetti, M.; Maierová, L.; Cajochen, C.; Scartezzini, J. -L.; Münch, M.

Optimized office lighting advances melatonin phase and peripheral heat loss prior bedtime Journal Article

In: Scientific Reports, vol. 12, pp. 4267, 2022.

Birchler-Pedross, A.; Frey, S.; Cajochen, C.; Chellappa, S. L.

Circadian and sleep modulation of dreaming in women with major depression Journal Article

In: Clocks & Sleep, vol. 4, no. 1, pp. 114-128, 2022.

Cajochen, C.; Stefani, O.; Schöllhorn, I.; Lang, D.; Chellappa, S.

Influence of evening light exposure on polysomnographically assessed night-time sleep: A systematic review with meta-analysis Journal Article

In: Lighting Research & Technology, vol. 54, pp. 609-654, 2022.

@article{Cajochen2022,

title = {Influence of evening light exposure on polysomnographically assessed night-time sleep: A systematic review with meta-analysis },

author = {C. Cajochen and O. Stefani and I. Schöllhorn and D. Lang and S. Chellappa},

doi = {https://doi.org/10.1177/14771535221078765},

year  = {2022},

date = {2022-01-10},

urldate = {2022-01-10},

journal = {Lighting Research & Technology},

volume = {54},

pages = {609-654},

abstract = {Evening exposure to electric light can acutely suppress melatonin levels and adversely affect subsequent sleep. We conducted a systematic review with meta-analysis investigating the influence of evening illuminance levels on polysomnographically (PSG)-assessed sleep. We also explored how melanopsin (expressed in melanopic equivalent daylight illuminance (EDI) affects human sleep features. We included polysomnographic laboratory sleep studies with healthy humans for effects of illuminance and exposure duration, for pre-sleep exposures between 6:00 p.m. to 1:00 a.m. From 440 identified articles, 114 met eligibility criteria for screening, and 21 also reported type of light source/spectral characteristics, with 12 identified as eligible for review. Meta-analysis showed evening light affects sleep latency, sleep efficiency and slow wave sleep, with overall effect sizes (95% confidence interval) of 0.69 (−0.50; 1.88), 0.34 (−0.13; 0.82) and −0.61 (−1.85; 0.62), respectively. Estimated melanopic EDI in the range of 100–1000 lx yielded clear dose–response relationships for sleep latency and sleep efficiency, but not for slow wave sleep. Whilst illuminance and duration indicated no apparent effects for a single evening light exposure on PSG-assessed sleep latency, sleep efficiency and slow wave sleep, we observed evidence for a relationship between light exposure and sleep effects based on melanopic EDI. Hence, melanopic EDI may provide a robust predictor of non-visual responses on human sleep.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Predicting melatonin suppression by light in humans: unifying photoreceptor-based equivalent daylight illuminances, spectral composition, timing and duration of light exposure Journal Article

Gimenez, M.; Stefani, O.; Cajochen, C.; Lang, D.; Deuring, G.; Schlangen, L. J. M.

In: Journal of Pineal Research, 2022.

@article{Gimenez2022,

title = {Predicting melatonin suppression by light in humans: unifying photoreceptor-based equivalent daylight illuminances, spectral composition, timing and duration of light exposure},

author = {M. Gimenez and O. Stefani and C. Cajochen and D. Lang and G. Deuring and L.J.M. Schlangen},

doi = { https://doi.org/10.1111/jpi.12786},

year  = {2022},

date = {2022-01-03},

journal = {Journal of Pineal Research},

abstract = {Light-induced melatonin suppression data from 29 peer-reviewed publications was analysed by means of a machine learning approach to establish which light exposure characteristics (i.e. photopic illuminance, five α-opic equivalent daylight illuminances (EDIs), duration and timing of the light exposure, and the dichotomous variables pharmacological pupil dilation and narrowband light source) are the main determinants of melatonin suppression. Melatonin suppression in the dataset was dominated by four light exposure characteristics: 1. melanopic EDI, 2. light exposure duration, 3. pupil dilation and 4. S-cone-opic EDI. A logistic model was used to evaluate the influence of each of these parameters on the melatonin suppression response. The final logistic model was only based on the first three parameters, since melanopic EDI was the best single (photoreceptor) predictor that was only outperformed by S-cone-opic EDI for (photopic) illuminances below 21 lux. This confirms and extends findings on the importance of the metric melanopic EDI for predicting biological effects of light in integrative (human centric) lighting applications. The model provides initial and general guidance to lighting practitioners on how to combine spectrum, duration and amount of light exposure when controlling non-visual responses to light, especially melatonin suppression. The model is a starting tool for developing hypotheses on photoreceptors’ contributions to light’s non-visual responses and helps identifying areas where more data is needed, like on the S-cone contribution at low illuminances.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Cajochen, C.; Weber, J.; Estrada, A. J.; Kobayashi, K.; Gabel, V.

Circadian and homeostatic sleep-wake regulation of secretory immunoglobulin A (sIgA): Effects of environmental light and recovery sleep Journal Article

In: Brain, Behaviour, Immunity, & Health, pp. 100394, 2021.

Spitschan, M.; Garbazza, C.; Kohl, S.; Cajochen, C.

Sleep and circadian phenotype in people without cone-mediated vision: a case series of five CNGB3 and two CNGA3 patients Journal Article

In: Brain Communications, 2021.

@article{Spitschan2021,

title = {Sleep and circadian phenotype in people without cone-mediated vision: a case series of five CNGB3 and two CNGA3 patients},

author = {M. Spitschan and C. Garbazza and S. Kohl and C. Cajochen},

url = {http://www.chronobiology.ch/wp-content/uploads/2021/09/fcab159.pdf},

doi = {10.1093/braincomms/fcab159},

year  = {2021},

date = {2021-07-18},

journal = {Brain Communications},

abstract = {Light exposure entrains the circadian clock through the intrinsically photosensitive retinal ganglion cells, which sense light in addition to the cone and rod photoreceptors. In congenital achromatopsia (prevalence 1:30–50 000), the cone system is non-functional, resulting in severe light avoidance and photophobia at daytime light levels. How this condition affects circadian and neuroendocrine responses to light is not known. In this case series of genetically confirmed congenital achromatopsia patients (n = 7; age 30–72 years; 6 women, 1 male), we examined survey-assessed sleep/circadian phenotype, self-reported visual function, sensitivity to light and use of spectral filters that modify chronic light exposure. In all but one patient, we measured rest-activity cycles using actigraphy over 3 weeks and measured the melatonin phase angle of entrainment using the dim-light melatonin onset. Owing to their light sensitivity, congenital achromatopsia patients used filters to reduce retinal illumination. Thus, congenital achromatopsia patients experienced severely attenuated light exposure. In aggregate, we found a tendency to a late chronotype. We found regular rest-activity patterns in all patients and normal phase angles of entrainment in participants with a measurable dim-light melatonin onset. Our results reveal that a functional cone system and exposure to daytime light intensities are not necessary for regular behavioural and hormonal entrainment, even when survey-assessed sleep and circadian phenotype indicated a tendency for a late chronotype and sleep problems in our congenital achromatopsia cohort.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Weibel, J.; Lin, Y. -S.; Landolt, H. -P.; Berthomier, C.; Brandenwinder, M.; Kistler, J.; Rehm, S.; Rentsch, K.; Meyer, M.; Borgwardt, S.; Cajochen, C.; Reichert, C. F.

Regular caffeine intake delays REM sleep promotion and attenuates sleep quality in healthy men Journal Article

In: Journal of Biological Rhythms, 2021.

@article{Weibel2021b,

title = {Regular caffeine intake delays REM sleep promotion and attenuates sleep quality in healthy men},

author = {J. Weibel and Y.-S. Lin and H.-P. Landolt and C. Berthomier and M. Brandenwinder and J. Kistler and S. Rehm and K. Rentsch and M. Meyer and S. Borgwardt and C. Cajochen and C. F. Reichert },

url = {https://journals.sagepub.com/doi/pdf/10.1177/07487304211013995},

doi = {10.1177/07487304211013995},

year  = {2021},

date = {2021-05-23},

journal = {Journal of Biological Rhythms},

abstract = {Acute  caffeine  intake  can  attenuate  homeostatic  sleep  pressure  and  worsen  sleep  quality.  Caffeine  intake—particularly  in  high  doses  and  close  to  bedtime—may  also  affect  circadian-regulated  rapid  eye  movement  (REM)  sleep  promotion,  an  important  determinant  of  subjective  sleep  quality.  However,  it  is  not  known  whether  such  changes  persist  under  chronic  caffeine  consumption  during  daytime.  Twenty  male  caffeine  consumers  (26.4  ±  4  years  old,  habitual  caffeine  intake  478.1  ±  102.8  mg/day)  participated  in  a  double-blind  crossover  study. Each volunteer completed a caffeine (3 × 150 mg caffeine daily for 10 days), a withdrawal (3 × 150 mg caffeine for 8 days then placebo), and a placebo condition. After 10 days of controlled intake and a fixed sleep-wake cycle, we recorded electroencephalography  for  8  h  starting  5  h  after  habitual  bedtime  (i.e.,  start  on  average at 04:22 h which is around the peak of circadian REM sleep promotion). A 60-min evening nap preceded each sleep episode and reduced high sleep pres-sure levels. While total sleep time and sleep architecture did not significantly differ between the three conditions, REM sleep latency was longer after daily caffeine intake compared with both placebo and withdrawal. Moreover, the accumulation of REM sleep proportion was delayed, and volunteers reported more difficulties with awakening after sleep and feeling more tired upon wake-up in the caffeine condition  compared  with  placebo.  Our  data  indicate  that  besides  acute  intake,  also  regular  daytime  caffeine  intake  affects  REM  sleep  regulation  in  men,  such  that  it  delays  circadian  REM  sleep  promotion  when  compared  with  placebo.  Moreover, the observed caffeine-induced deterioration in the quality of awakening may suggest a potential motive to reinstate caffeine intake after sleep.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Stefani, O.; Cajochen, C.

Should We Re-think Regulations and Standards for Lighting at Workplaces? A Practice Review on Existing Lighting Recommendations Journal Article

In: Frontiers in psychiatry, vol. 12, 2021.

Blume, C.; Cajochen, C.

‘SleepCycles’ package for R - A free software tool for the detection of sleep cycles from sleep staging Journal Article

In: MethodsX, 2021.

Daily Caffeine Intake Induces Concentration-Dependent Medial Temporal Plasticity in Humans: A Multimodal Double-Blind Randomized Controlled Trial Journal Article

Lin, Y. -S.; Weibel, J.; Landolt, H.; Santini, F.; Meyer, M.; Brunmair, J.; Meyer-Menches, S.; gerner, C.; Borgwardt, S.; Cajochen, C.; Reichert, C. F.

In: Cerebral Cortex, 2021.

@article{Lin2021,

title = {Daily Caffeine Intake Induces Concentration-Dependent Medial Temporal Plasticity in Humans: A Multimodal Double-Blind Randomized Controlled Trial },

author = { Y.-S. Lin and J. Weibel and H. Landolt and F. Santini and M. Meyer and J. Brunmair and S. Meyer-Menches and C. gerner and S. Borgwardt and C. Cajochen and C. F. Reichert},

url = {http://www.chronobiology.ch/wp-content/uploads/2021/02/Lin_2021_CC_acc_uncorrect.pdf},

doi = {doi.org/10.1093/cercor/bhab005},

year  = {2021},

date = {2021-02-15},

journal = {Cerebral Cortex},

abstract = {Caffeine is commonly used to combat high sleep pressure on a daily basis. However, interference with sleep–wake regulation could disturb neural homeostasis and insufficient sleep could lead to alterations in human gray matter. Hence, in this double-blind, randomized, cross-over study, we examined the impact of 10-day caffeine (3 × 150 mg/day) on human gray matter volumes (GMVs) and cerebral blood flow (CBF) by fMRI MP-RAGE and arterial spin-labeling sequences in 20 habitual caffeine consumers, compared with 10-day placebo (3 × 150 mg/day). Sleep pressure was quantified by electroencephalographic slow-wave activity (SWA) in the previous nighttime sleep. Nonparametric voxel-based analyses revealed a significant reduction in GMV in the medial temporal lobe (mTL) after 10 days of caffeine intake compared with 10 days of placebo, voxel-wisely adjusted for CBF considering the decreased perfusion after caffeine intake compared with placebo. Larger GMV reductions were associated with higher individual concentrations of caffeine and paraxanthine. Sleep SWA was, however, neither different between conditions nor associated with caffeine-induced GMV reductions. Therefore, the data do not suggest a link between sleep depth during daily caffeine intake and changes in brain morphology. In conclusion, daily caffeine intake might induce neural plasticity in the mTL depending on individual metabolic processes.},

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pubstate = {published},

tppubtype = {article}

}

Stefani, O.; Freyburger, M.; Veitz, S.; Basishvili, T.; Meyer, M.; Weibel, J.; Kobayashi, K.; Shirakawa, Y.; Cajochen, C.

Changing color and intensity of LED lighting across the day impacts on circadian melatonin rhythms and sleep in healthy men Journal Article

In: Journal of Pineal Research, vol. 70, 2020.

Blume, C.; Schmidt, Marlene H.; Cajochen, C.

Effects of the COVID-19 lockdown on human sleep and rest-activity rhythms Journal Article

In: Current Biology, 2020.

@article{Blume2020b,

title = {Effects of the COVID-19 lockdown on human sleep and rest-activity rhythms},

author = {C. Blume and Marlene H. Schmidt and C. Cajochen},

url = {http://www.chronobiology.ch/wp-content/uploads/2021/09/1-s2.0-S096098222030837X-main.pdf},

doi = {https://doi.org/10.1016/j.cub.2020.06.021},

year  = {2020},

date = {2020-06-10},

journal = {Current Biology},

abstract = {In modern societies, human rest-activity rhythms and sleep result from the tensions and dynamics between the conflicting poles of external social time (e.g., work hours and leisure activities) and an individual’s internal biological time. A mismatch between the two has been suggested to induce ‘social jetlag’ [SJL; 1] and ‘social sleep restriction’ (SSR), that is, shifts in sleep timing and differences in sleep duration between work days and free days. Social jetlag [2, 3] and sleep restrictions [4] have repeatedly been associated with negative consequences on health, mental wellbeing, and performance. In a large-scale quasi-experimental design, we investigated the effects of the phase with the strictest COVID-19 restrictions on the relationship between social and biological rhythms as well as sleep during a six-week period (mid-March until end of April 2020) in three European societies (Austria, Germany, Switzerland). We found that, on one hand, the restrictions reduced the mismatch between external (social) and internal (biological) sleep-wake timing, as indexed by significant reductions in SJL and SSR, with a concomitant increase in sleep duration. Sleep quality on the other hand was slightly reduced. The improved individual sleep-wake timing can presumably be attributed to an increased flexibility of social schedules, for instance due to more work being accomplished from home. However, this unprecedented situation also led to a significant increase in self-perceived burden, which was attendant to the decrease in sleep quality. These adverse effects may be alleviated by exposure to natural daylight as well as physical exercising.},

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pubstate = {published},

tppubtype = {article}

}

Genome-Wide DNA Methylation in Peripheral Blood and Long-Term Exposure to Source-Specific Transportation Noise and Air Pollution: The SAPALDIA Study Journal Article

Eze, I. C.; Jeong, A.; Schaffner, E.; Rezwan, F. I.; Ghantous, A.; Foraster, M.; Vienneau, D.; F, F. Kronenberg; Herceg, Z.; Vineis, P.; Brink, M.; Wunderli, J. M.; Schindler, C.; Cajochen, C.; M, M. Röösli; Holloway, J. W.; Imboden, M.; Probst-Hensch, N.

In: Environ Health Perspect, vol. 128, no. 6, pp. 67003, 2020.

Study Protocol for a Prospective Randomised Double-Blind Placebo-Controlled Clinical Trial Investigating a Better Outcome With Melatonin Compared to Placebo Administered to Normalize Sleep-Wake Cycle and Treat Hypoactive ICU Delirium: The Basel BOMP-AID Study Journal Article

Hollinger, A.; von Felten, S.; Sutter, R.; Huber, J.; Tran, F.; Reinhold, S.; Abdelhamid, S.; Todorov, A.; Gebhard, C. E.; Cajochen, C.; Steiner, L. A; Siegemund, M.

In: BMJ Open, 2020.

Weibel, J.; Lin, Y. -S.; Landolt, H. -P.; Garbazza, C.; Kolodyazhniy, V.; Kistler, J.; Rehm, S.; Rentsch, K.; Borgwardt, S.; Cajochen, C.; Reichert, C. F.

Caffeine-dependent changes of sleep-wake regulation: Evidence foradaptation after repeated intake Journal Article

In: Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2020.

@article{Weibel2020,

title = {Caffeine-dependent changes of sleep-wake regulation: Evidence foradaptation after repeated intake},

author = {J. Weibel and Y.-S. Lin and H.-P. Landolt and C. Garbazza and V. Kolodyazhniy and J. Kistler and S. Rehm and K. Rentsch and S. Borgwardt and C. Cajochen and C. F. Reichert },

url = {http://www.chronobiology.ch/1-s2-0-s0278584619304798-main-2/},

doi = {10.1016/j.pnpbp.2019.109851 },

year  = {2020},

date = {2020-04-20},

journal = {Progress in Neuro-Psychopharmacology and Biological Psychiatry},

abstract = {Background: Circadian and sleep-homeostatic mechanisms regulate timing and quality of wakefulness. To enhance wakefulness, daily consumption of caffeine in the morning and afternoon is highly common. However, the effects of such a regular intake pattern on circadian sleep-wake regulation are unknown. Thus, we investigated if daily daytime caffeine intake and caffeine withdrawal affect circadian rhythms and wake-promotion in habitual consumers.

Methods: Twenty male young volunteers participated in a randomised, double-blind, within-subject study with three conditions: i) caffeine (150 mg 3 x daily for 10 days), ii) placebo (3 x daily for 10 days) and iii) withdrawal (150 mg caffeine 3 x daily for eight days, followed by a switch to placebo for two days). Starting on day nine of treatment, salivary melatonin and cortisol, evening nap sleep as well as sleepiness and vigilance performance throughout day and night were quantified during 43 h in an in-laboratory, light and posture-controlled protocol.

Results: Neither the time course of melatonin (i.e. onset, amplitude or area under the curve) nor the time course of cortisol was significantly affected by caffeine or withdrawal. During withdrawal, however, volunteers reported increased sleepiness, showed more attentional lapses as well as polysomnography-derived markers of elevated sleep propensity in the late evening compared to both the placebo and caffeine condition.

Conclusions: The typical pattern of caffeine intake with consumption in both the morning and afternoon hours may not necessarily result in a circadian phase shift in the evening nor lead to clear-cut benefits in alertness. The time-of-day independent effects of caffeine withdrawal on evening nap sleep, sleepiness and performance suggest an adaptation to the substance, presumably in the homeostatic aspect of sleep-wake regulation.},

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tppubtype = {article}

}

Chellappa, S. L.; Bromundt, V.; Frey, S.; Schlote, T.; Goldblum, D.; Cajochen, C.; Reichert, C. F.

Intraocular cataract lens replacement and light exposure potentially impact procedural learning in older adults Journal Article

In: 2020.

Rudzik, F.; Thiesse, L.; Pieren, R.; Héritier, H.; Eze, I. C; Foraster, M.; Vienneau, D.; Brink, M.; Wunderli, J. M.; Probst-Hensch, N.; Röösli, M.; Fulda, S.; Cajochen, C.

Ultradian Modulation of Cortical Arousals During Sleep: Effects of Age and Exposure to Nighttime Transportation Noise Journal Article

In: Sleep, 2020.

Spitschan, M.; Lazar, R.; Yetik, E.; Cajochen, C.

No evidence for an S cone contribution to acute neuroendocrine and alerting responses to light Journal Article

In: Current Biology, 2019.

Spitschan, M.; Lazar, R.; Cajochen, C.

Visual and non-visual properties of filters manipulating short-wavelength light Journal Article

In: Ophthalmic Physiol Opt, 2019.

Lasauskaite, R; Hazelhoff, E M; Cajochen, C.

Four minutes might not be enough for color temperature of light to affect subjective sleepiness, mental effort, and light ratings Journal Article

In: Lighting Research & Technology, vol. 51, iss. 7, pp. 1128–1138, 2019.

Lasauskaite, R; Cajochen, C.

Influence of lighting color temperature on effort-related cardiac response Journal Article

In: Biological Psychology, vol. 132, pp. doi:10.1016/j.biopsycho.2017.11.005, 2018.

Chellappa, S L; Lasauskaite, R; Cajochen, C.

In a Heartbeat: Light and Cardiovascular Physiology Journal Article

In: Frontiers in Neurology, vol. 8, pp. doi:10.3389/fneur.2017.00541, 2017.

Differential impact in young and older individuals of blue-enriched white light on circadian physiology and alertness during sustained wakefulness Journal Article

Gabel, V.; Reichert, C. F.; Maire, M.; Schmidt, C.; Schlangen, L. J. M.; Kolodyazhniy, V.; Garbazza, C.; Cajochen, C.; Viola, A. U.

In: Scientific Reports, vol. 7, no. 7620, pp. doi:doi:10.1038/s41598-017-07060-8, 2017.

Reichert, C. F.; Maire, M.; Gabel, V.; Viola, A. U.; Götz, T.; Scheffler, K.; Klarhöfer, M.; Berthomier, C.; Strobel, W.; Phillips, C.; Salmon, E.; Cajochen, C.; Schmidt, C.

Cognitive brain responses during circadian wake-promotion: evidence for sleep-pressure-dependent hypothalamic activations Journal Article

In: Scientific Reports, vol. 7, pp. doi:10.1038/s41598-017-05695-1, 2017.

Reichert, C. F.; Maire, M.; Schmidt, C.; Cajochen, C.

Sleep-wake regulation and its impact on working memory performance: the role of adenosine Journal Article

In: Biology, vol. 5, no. 1, pp. E11. doi:10.3390/biology5010011., 2016.

Garbazza, C.; Bromundt, V.; Eckert, A.; Brunner, D. P.; Meier, F.; Hackethal, S.; Cajochen, C.

Non-24-Hour Sleep-Wake Disorder Revisited - A Case Study Journal Article

In: Front Neurol. 2016 Feb 29;7:17 doi: 10.3389/fneur.2016.00017, 2016.

Schmidt, C.; Collette, F.; Reichert, C. F.; Maire, M.; Vandewalle, G.; Peigneux, P.; Cajochen, C.

Pushing the limits: chronotype and time of day modulate working memory-dependent cerebral activity Journal Article

In: Frontiers in Neurology, vol. 25, no. 6:199, pp. 1-9, 2015.

Gabel, V.; Maire, M.; Reichert, C. F.; Chellappa, S. L.; Schmidt, C.; Hommes, V.; Cajochen, C.; Viola, A. U.

Dawn simulation light impacts on different cognitive domains under sleep restriction Journal Article

In: Behav Brain Res., doi: 10.1016/j.bbr.2014.12.043, vol. 15, pp. 281: 258-266, 2015.

Maire, M.; Reichert, C. F.; Gabel, V.; Viola, A. U.; Phillips, C.; Krebs, J.; Scheffler, K.; Klarhöfer, M.; Strobel, W.; Cajochen, C.; Schmidt, C.

Fighting Sleep at Night: Brain Correlates and Vulnerability to Sleep Loss Journal Article

In: Ann Neurol., doi: 10.1002/ana.24434., vol. 78(2), pp. 235-247, 2015.

vanderLely, S.; Frey, S.; Garbazza, C.; Wirz-Justice, A.; Jenni, O. G.; Steiner, R.; Wolf, S.; Cajochen, C.; Bromundt, V.; Schmidt, C.

Blue blocker glasses as a countermeasure for alerting effects of evening light-emitting diode screen exposure in male teenagers Journal Article

In: J Adolesc Health, doi: 10.1016/j.jadohealth.2014.08.002, vol. 56(1), pp. 113-119, 2015.

Reichert, C. F.; Maire, M.; Gabel, V.; Hofstetter, M.; Viola, A. U.; Kolodyazhniy, V.; Strobel, W.; Goetz, T.; Bachmann, V.; Landolt, H. -P.; Cajochen, C.; Schmidt, C.

The Circadian Regulation of Sleep: Impact of a Functional ADA-Polymorphism and Ist Association to Working Memory Journal Article

In: PLoS ONE, vol. 9, no. 12, pp. 1-23, 2014.

Chellappa, S. L.; Viola, A. U.; Schmidt, C.; Bachmann, V.; Gabel, V.; Maire, M.; Reichert, C. F.; Valomon, A.; Landolt, H. P.; Cajochen, C.

Light modulation of human sleep depends on a polymorphism in the clock gene Period3 Journal Article

In: Behavioural Brain Research, vol. 271, pp. 23-29, 2014.

Reichert, C. F.; Maire, M.; Gabel, V.; Viola, A. U.; Kolodyazhniy, V.; Strobel, W.; Götz, T.; Bachmann, V.; Landolt, H. P.; Cajochen, C.; Schmidt, C.

Insights into Behavioral Vulnerability to Differential Sleep Pressure and Circadian Phase from a Functional ADA Polymorphism Journal Article

In: Journal of Biological Rhythms, vol. 29, no. 2, pp. 119-130, 2014.

@article{,

title = {Insights into Behavioral Vulnerability to Differential Sleep Pressure and Circadian Phase from a Functional ADA Polymorphism},

author = {C. F. Reichert and M. Maire and V. Gabel and A.U. Viola and V. Kolodyazhniy and W. Strobel and T. Götz and V. Bachmann and H.P. Landolt and C. Cajochen and C. Schmidt},

url = {http://www.chronobiology.ch/wp-content/uploads/2014/04/Reichert-2014-behavioral-vulnerability1.pdf},

year  = {2014},

date = {2014-04-02},

journal = {Journal of Biological Rhythms},

volume = {29},

number = {2},

pages = {119-130},

abstract = {Sleep loss affects human behavior in a nonuniform manner, depending

on the cognitive domain and also the circadian phase. Besides, evidence

exists about stable interindividual variations in sleep loss–related performance

impairments. Despite this evidence, only a few studies have considered both

circadian phase and neurobehavioral domain when investigating trait-like

vulnerability to sleep manipulation. By applying a randomized, crossover

design with 2 sleep pressure conditions (40 h sleep deprivation vs. 40 h multiple

naps), we investigated the influence of a human adenosine deaminase

(ADA) polymorphism (rs73598374) on several behavioral measures throughout

nearly 2 circadian cycles. Confirming earlier studies, we observed that

under sleep deprivation the previously reported vulnerable G/A-allele carriers

felt overall sleepier than G/G-allele carriers. As expected, this difference

was no longer present when sleep pressure was reduced by the application of

multiple naps. Concomitantly, well-being was worse in the G/A genotype

under sleep loss when compared to the nap protocol, and n-back working

memory performance appeared to be specifically susceptible to sleep-wake

manipulation in this genotype. When considering psychomotor vigilance performance, however, a higher sensitivity to sleep-wake manipulation was detected in homozygous participants, but specifically at the end of the night

and only for optimal task performance. Although these data are based on a

small sample size and hence require replication (12 G/A- and 12 G/G-allele

carriers), they confirm the assumption that interindividual differences regarding

the effect of sleep manipulation highly depend on the cognitive task and

circadian phase, and thus emphasize the necessity of a multimethodological

approach. Moreover, they indicate that napping might be suitable to counteract endogenously heightened sleep pressure depending on the neurobehavioral

domain.},

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pubstate = {published},

tppubtype = {article}

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Maire, M.; Reichert, C. F.; Gabel, V.; Viola, A. U.; Krebs, J.; Strobel, W.; Landolt, H. P.; Bachmann, V.; Cajochen, C.; Schmidt, C.

Time-on-task decrement in vigilance is modulated by inter-individual vulnerability to homeostatic sleep pressure manipulation Journal Article

In: Frontiers in Behavioral Neuroscience, vol. 8, no. 59, 2014, ISSN: 1662-5153.

@article{,

title = {Time-on-task decrement in vigilance is modulated by inter-individual vulnerability to homeostatic sleep pressure manipulation},

author = {M. Maire and C. F. Reichert and V. Gabel and A.U. Viola and J. Krebs and W. Strobel and H.P. Landolt and V. Bachmann and C. Cajochen and C. Schmidt},

url = {http://www.chronobiology.ch/wp-content/uploads/2014/03/Timeontask_MAIREetal2014.pdf},

issn = {1662-5153},

year  = {2014},

date = {2014-03-06},

journal = {Frontiers in Behavioral Neuroscience},

volume = {8},

number = {59},

abstract = {Under sleep loss, vigilance is reduced and attentional failures emerge progressively. It becomes difficult to maintain stable performance over time, leading to growing performance variability (i.e., state instability) in an individual and among subjects. Task duration plays a major role in the maintenance of stable vigilance levels, such that the longer the task, the more likely state instability will be observed. Vulnerability to sleep-loss-dependent performance decrements is highly individual and is also modulated by a polymorphism in the human clock gene PERIOD3 (PER3). By combining two different protocols, we manipulated sleep-wake history by once extending wakefulness for 40 h (high sleep pressure condition) and once by imposing a short sleep-wake cycle by alternating 160 min of wakefulness and 80 min naps (low sleep pressure condition) in a within-subject design. We observed that homozygous carriers of the long repeat allele of PER3 (PER35/5) experienced a greater time-on-task dependent performance decrement (i.e., a steeper increase in the number of lapses) in the Psychomotor Vigilance Task compared to the carriers of the short repeat allele (PER34/4). These genotype-dependent effects disappeared under low sleep pressure conditions, and neither motivation, nor perceived effort accounted for these differences. Our data thus suggest that greater sleep-loss related attentional vulnerability based on the PER3 polymorphism is mirrored by a greater state instability under extended wakefulness in the short compared to the long allele carriers. Our results undermine the importance of time-on-task related aspects when investigating inter-individual differences in sleep loss-induced behavioral vulnerability.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Maire, M.; Reichert, C. F.; Gabel, V.; Viola, A. U.; Strobel, W.; Krebs, J.; Landolt, H. P.; Bachmann, V.; Cajochen, C.; Schmidt, C.

Sleep ability mediates individual differences in the vulnerability to sleep loss: Evidence from a PER3 polymorphism Journal Article

In: Cortex, vol. http://dx.doi.org/10.1016/j.cortex.2013., 2014.

Gabel, V.; Maire, M.; Reichert, C. F.; Chellappa, S. L.; Schmidt, C.; Hommes, V.; Viola, A. U.; Cajochen, C.

Effects of Artificial Dawn and Morning Blue Light on Daytime Cognitive Performance, Well-being, Cortisol and Melatonin Levels Journal Article

In: Chronobiology International, vol. 30, pp. 988-97, 2013.

@article{180,

title = {Effects of Artificial Dawn and Morning Blue Light on Daytime Cognitive Performance, Well-being, Cortisol and Melatonin Levels},

author = {V. Gabel and M. Maire and C. F. Reichert and S.L. Chellappa and C. Schmidt and V. Hommes and A.U. Viola and C. Cajochen},

url = {http://www.chronobiology.ch/wp-content/uploads/publications/Gabel_2013.pdf},

year  = {2013},

date = {2013-07-10},

journal = {Chronobiology International},

volume = {30},

pages = {988-97},

abstract = {Light exposure elicits numerous effects on human physiology and behavior, such as better cognitive performance and

mood. Here we investigated the role of morning light exposure as a countermeasure for impaired cognitive

performance and mood under sleep restriction (SR). Seventeen participants took part of a 48h laboratory protocol,

during which three different light settings (separated by 2 wks) were administered each morning after two 6-h sleep

restriction nights: a blue monochromatic LED (light-emitting diode) light condition (BL; 100 lux at 470 nm for 20 min)

starting 2 h after scheduled wake-up time, a dawn-simulating light (DsL) starting 30 min before and ending 20 min

after scheduled wake-up time (polychromatic light gradually increasing from 0 to 250 lux), and a dim light (DL)

condition for 2 h beginning upon scheduled wake time (58 lux). Cognitive tasks were performed every 2 h during

scheduled wakefulness, and questionnaires were administered hourly to assess subjective sleepiness, mood, and wellbeing. Salivary melatonin and cortisol were collected throughout scheduled wakefulness in regular intervals, and the

effects on melatonin were measured after only one light pulse. Following the first SR, analysis of the time course of

cognitive performance during scheduled wakefulness indicated a decrease following DL, whereas it remained stable

following BL and significantly improved after DsL. Cognitive performance levels during the second day after SR were

not significantly affected by the different light conditions. However, after both SR nights, mood and well-being were

significantly enhanced after exposure to morning DsL compared with DL and BL. Melatonin onset occurred earlier

after morning BL exposure, than after morning DsL and DL, whereas salivary cortisol levels were higher at wake-up

time after DsL compared with BL and DL. Our data indicate that exposure to an artificial morning dawn simulation

light improves subjective well-being, mood, and cognitive performance, as compared with DL and BL, with minimal

impact on circadian phase. Thus, DsL may provide an effective strategy for enhancing cognitive performance, wellbeing, and mood under mild sleep restriction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Light exposure elicits numerous effects on human physiology and behavior, such as better cognitive performance and
mood. Here we investigated the role of morning light exposure as a countermeasure for impaired cognitive
performance and mood under sleep restriction (SR). Seventeen participants took part of a 48h laboratory protocol,
during which three different light settings (separated by 2 wks) were administered each morning after two 6-h sleep
restriction nights: a blue monochromatic LED (light-emitting diode) light condition (BL; 100 lux at 470 nm for 20 min)
starting 2 h after scheduled wake-up time, a dawn-simulating light (DsL) starting 30 min before and ending 20 min
after scheduled wake-up time (polychromatic light gradually increasing from 0 to 250 lux), and a dim light (DL)
condition for 2 h beginning upon scheduled wake time (58 lux). Cognitive tasks were performed every 2 h during
scheduled wakefulness, and questionnaires were administered hourly to assess subjective sleepiness, mood, and wellbeing. Salivary melatonin and cortisol were collected throughout scheduled wakefulness in regular intervals, and the
effects on melatonin were measured after only one light pulse. Following the first SR, analysis of the time course of
cognitive performance during scheduled wakefulness indicated a decrease following DL, whereas it remained stable
following BL and significantly improved after DsL. Cognitive performance levels during the second day after SR were
not significantly affected by the different light conditions. However, after both SR nights, mood and well-being were
significantly enhanced after exposure to morning DsL compared with DL and BL. Melatonin onset occurred earlier
after morning BL exposure, than after morning DsL and DL, whereas salivary cortisol levels were higher at wake-up
time after DsL compared with BL and DL. Our data indicate that exposure to an artificial morning dawn simulation
light improves subjective well-being, mood, and cognitive performance, as compared with DL and BL, with minimal
impact on circadian phase. Thus, DsL may provide an effective strategy for enhancing cognitive performance, wellbeing, and mood under mild sleep restriction.

Chellappa, S. L.; Viola, A. U.; Schmidt, C.; Bachmann, V.; Gabel, V.; Maire, M.; Reichert, C. F.; Valomon, A.; Götz, T.; Landolt, H. P.; Cajochen, C.

Human melatonin and alerting response to blue-enriched light depend on a polymorphism in the clock gene PER3 Journal Article

In: J Clin Endocrinol Metab 97(3), 2011.