Background
Our sleep quality and sleep rhythm are influenced by many environmental factors. Caffeine, for example, promotes wakefulness and reduces sleep pressure. Light in the evening shifts the internal clock. Such environmental conditions can be associated with negative consequences (such as reduced sleep duration or sleep quality), especially in adolescents, because their sleep pressure in the evening is already lower and their biological rhythm is often delayed. Studies show that caffeine can even further amplify the light-induced shift in the evening. It remains unclear whether caffeine can also enhance the positive effects of light in the morning—which would be desirable, because morning light promotes wakefulness, improves mood, and synchronizes the internal clock with the social daily rhythm.
Research Project
In the chronobiology laboratory, we are investigating whether caffeine enhances the effects of light in the morning. Adolescents and adults receive light therapy and a tablet containing either caffeine or a placebo after about six hours of sleep. During the study, we measure, among other things, the timing of the internal clock via hormone concentrations (melatonin and cortisol in saliva), as well as alertness, mood, tension, sleep, and performance using brain activity recordings (so-called electroencephalography, EEG), questionnaires, and reaction tests. In addition, we record pupil size and the light sensitivity of the retina to better understand how light is processed under the influence of caffeine.
The project provides fundamental knowledge about the regulation of the internal clock. Particular attention is given to adolescents: they may benefit from a more efficient synchronization through caffeine but are also sensitive to its sleep-disrupting effects. The study contributes to a better understanding of the benefits and risks of a stimulant that is widely used worldwide in everyday life.
Collaborations
Prof. Dr. Manuel Spitschan, TUM School of Medicine and Health, Technical University of Munich Germany
Prof. Leila Tarokh, University Clinics UPD of Bern, Switzerland
Sebastien Buchwalder, Oculox Technologies, Muzzano Switzerland
Funding
Swiss National Science Foundation
Study team
