Why do you wake up in the middle of the night?
Sleep is governed by two opposing systems:
The sleep system, which includes your circadian rhythm (your internal clock) and sleep pressure, the drive that builds the longer you stay awake.
The activation system, which keeps you alert and responsive during the day.
When these systems are balanced, the activation system quiets down at night and sleep naturally takes over. But sometimes—especially in the early morning hours—that balance is disrupted. The alert system stays switched on, overriding your body’s natural urge to sleep and causing sudden awakenings without an obvious reason.
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