Free-running sleep

Chronotype

Circadian rhythm

Neuroscience

Light effects on circadian rhythm

Biology

Dark therapy

Operating system

Psychiatry

Chronobiology

Computer science

Bacterial circadian rhythms

Phase response curve

Sleep (system call)

Nocturnal

Physics

Psychology

Circadian clock

Astronomy

Evening

Suprachiasmatic nucleus

Internal medicine

Melatonin

Rhythm

Mood

Electroencephalography

Medicine

Wakefulness

Somnologie - Schlafforschung und Schlafmedizin

Humans live in a 24-hour environment, in which light and darkness follow a diurnal pattern. Our circadian pacemaker, the suprachiasmatic nuclei (SCN) in the hypothalamus, is entrained to the 24-hour solar day via a pathway from the retina and synchronises our internal biological rhythms. Rhythmic variations in ambient illumination impact behaviours such as rest during sleep and activity during wakefulness as well as their underlying biological processes. Rather recently, the availability of artificial light has substantially changed the light environment, especially during evening and night hours. This may increase the risk of developing circadian rhythm sleep-wake disorders (CRSWD), which are often caused by a misalignment of endogenous circadian rhythms and external light-dark cycles. While the exact relationship between the availability of artificial light and CRSWD remains to be established, nocturnal light has been shown to alter circadian rhythms and sleep in humans. On the other hand, light can also be used as an effective and noninvasive therapeutic option with little to no side effects, to improve sleep,mood and general well-being. This article reviews our current state of knowledge regarding the effects of light on circadian rhythms, sleep, and mood.

Effects of light on human circadian rhythms, sleep and mood