Sleep Health
Cortisol, the sleep-wake cycle and the bidirectional loop between stress and insomnia.
Stress elevates evening cortisol, which directly opposes melatonin and delays sleep onset.
Chronic stress keeps the sympathetic nervous system in 'on' mode, preventing deep sleep.
Poor sleep increases next-day stress reactivity, which then worsens the following night's sleep.
Daily exercise, evening journaling, paced breathing and CBT-I all reduce both stress and insomnia.
Last reviewed March 2026 against current US sleep medicine guidelines by the Sleep Disorder Symptoms editorial team. This article is educational and is not medical advice — see our medical disclaimer and editorial policy.
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