Our inner clock
The biological clock plays an important role: It tells our body when it can be active and when it is time to downshift. It affects our bodily functions - blood pressure, body temperature, hormone balance.
Control center is a nerve nucleus in our brain - no bigger than a grain of rice. It lies at the level of the bridge of the nose above the intersection (chiasm) of the visual pathways, which is also where its name derives: suprachiasmatic nucleus, simpler: SCN. It is controlled by brain function and hormones and responds mainly to differences in light that are transmitted to it by special cells of the retina.
Out of rhythm
Things that used to be quite simple in the past are a constant challenge to our inner clock: whether night work or shift work, disco evenings, long-haul flights or time changes in spring and autumn - the days are longer by artificial light, the rhythms no longer correspond the light and dark times or change at short notice again and again.
Temporarily our organism can compensate for this, in the long run this heavy work leads to physical and mental disturbances. If the individual daily rhythm is constantly ignored, it can lead to sleep disorders, loss of performance and moods to depression, and the risk of physical illness increases.
Chronotypes: Of larks and owls
Another aspect is that there are different types of timepieces (chronotypes): the larks and the owls. They have different sleeping and waking times and differ in sleep duration. If they live - for example due to rigid working hours in school and working life - constantly contrary to their individual rhythm, the risk of problems increases as well.
Sleep researchers and time biologists are increasingly on the trail of these relationships in recent years. Chronobiology as an interdisciplinary science explores how biorhythms and internal and external (environmental) factors are related and what impact our lifestyle has on our health. The more insights that chronobiology gains, the louder the voices will become to make our everyday rhythms in schools, business, employment and leisure so flexible that we do not have to disregard our internal clock.