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It’s three or four o’clock in the morning. You suddenly open your eyes, silently, without a nightmare, for no apparent reason. The house is silent, the world seems frozen, and yet … you are awake and cannot fall asleep again immediately.
If this scene sounds familiar to you, you belong to the silent majority. Millions of people experience these nightly waking phases, almost always at the same time. This phenomenon, which has given rise to myths, spiritual beliefs and fears, is nevertheless based on very concrete mechanisms of the body and the brain.
So what really happens when you wake up at 3 or 4 a.m.?
The sleep cycle: an inherently fragile moment
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