Christian Cajochen

Host: Andries Kalsbeek a.kalsbeek@nin.knaw.nl
Hypothalamic Integration Mechanisms.

The Guest Speaker:
Christian Cajochen
Professor of Experimental Psychiatry
Head Centre for Chronobiology
Psychiatric University Hospital University of Basel

Title: Tuned to time: how rhythms and light modulate melatonin, sleep and dream recall.

Abstract:
This talk will explore the intricate interplay of biological rhythms – circadian, homeostatic and ultradian – and exogenous factors such as seasonal and lunar influences on human circadian physiology and sleep-wake behaviour. I will first focus on circadian physiology, highlighting how non-visual effects of light, primarily via intrinsically photosensitive retinal ganglion cells, influence human melatonin rhythms and sleep onset latency. Evidence will be presented that these non-image-forming effects of light show seasonal variability, even under controlled laboratory conditions. I will then discuss how the circadian timing system promotes wakefulness and sleep, as assessed by ultrashort sleep-wake protocols, emphasising its regulatory role in REM sleep and dream recall. Specific EEG features associated with successful dream recall will be presented, with a focus on differences in emotional recall depending on whether individuals awaken from NREM or REM sleep, and in women with major depression. Finally, the presentation will touch on emerging data suggesting a possible modulation of human sleep by lunar phases, an area still under debate.