Die Wissenschaft des Tiefschlafs

Deep sleep, or slow-wave sleep, is when the body does its most important repair work. Growth hormone peaks, muscles recover and the brain clears the metabolic by-products of the day.

Why the first 90 minutes matter

The longest and deepest slow-wave cycles happen early in the night. Protecting that first cycle has an outsized effect on how restored you feel the next morning.

Five rituals that help

Keep the bedroom cool, around 18 °C. Dim the lights an hour before bed and put screens away. Eat your last meal at least three hours before sleep. Gentle warmth on the shoulders or abdomen, as in Traditional Chinese Medicine, helps many people unwind. Finally, wake at the same time every day, even on weekends.

The takeaway

Sleep quality is built during the day. Small, consistent rituals compound into deeper nights and brighter mornings.