Are you a lark or an owl? Don’t worry—this isn’t a zoology test. Scientists use these two terms to describe the main sleep types. “Larks” are people who wake up very early, become alert and productive quickly, and can barely keep their eyes open in front of the TV by around 9 p.m. “Owls,” on the other hand, struggle to get out of bed in the morning but are capable of peak performance in the evening. The mixed type—without an animal label—tends to reach a mental and creative high in the late morning and a low in the early afternoon. 

A sensor in the brain

Researchers also refer to these as chronotypes with different biological rhythms. The internal clock determines the ideal daily schedule—and this central timekeeper really exists. It consists of a tiny cluster of nerve cells, about the size of a pinhead, located roughly two centimeters behind the bridge of the nose in the brain. It detects whether it is light or dark. In darkness, it sends a signal to the pineal gland, a hormone-producing gland in the brain. This gland produces, among other things, the hormone melatonin, which regulates our day-night rhythm. 

The first ChronoCity

is emerging The internal clock determines the times of day when physical or mental activities yield the best results, when blood pressure and body temperature rise, and when the digestive system is ready for food. This is crucial for individual well-being and performance. The German spa town of Bad Kissingen has recognized the potential of chronobiology and aims to become the world’s first “ChronoCity,” where various factors are designed to support healthy sleep—for both residents and health tourists. New findings from chronobiology are already being incorporated into urban planning, from public lighting to architectural projects. This example shows how sleep research can directly influence the quality of life for many people.