The Worst Time to Go to Bed, According to Sleep Doctors

By Adam Meyer, Sep 28, 2026

Melatonin and cortisol are two hormones critical to sleep, and both of them follow a precise daily schedule. Melatonin, which signals to your body that it’s time to sleep, peaks in the evening and declines as the night progresses. Cortisol, your body’s natural alerting hormone, increases in the early morning hours to prepare you for waking. Going to bed after midnight can put your sleep schedule out of sync with these natural rhythms, particularly if you’re also exposed to bright light late at night. “Melatonin, which is timed to sunlight and peaks in the evening, is now diminishing when you try to fall asleep after midnight,” says Alex Dimitriu, M.D. “Cortisol levels start to rise towards the morning. This is your body’s natural alarm clock.”

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