The stages of a sleep cycle
Sleep isn't a single state — it moves through stages: light sleep, deep (slow-wave) sleep, and REM sleep, cycling roughly every 90 minutes through the night.
Why deep sleep matters
Deep sleep is when the body does much of its physical restoration — tissue repair, immune function support, and growth hormone release. Waking up frequently can fragment this stage.
Why REM sleep matters
REM sleep is associated with memory consolidation and cognitive processing. Both deep and REM sleep need to occur in adequate amounts across the night for restorative rest.
What disrupts sleep cycles?
Stress, screen exposure before bed, irregular schedules, and an overactive mind at bedtime can all interfere with moving smoothly through these cycles.
Where ingredients like melatonin and valerian root fit in
Ingredients such as melatonin support the circadian signal that initiates sleep, while valerian root and chamomile are associated with supporting sleep quality through the night. See our Melatonin article for more detail.
When to see a doctor
Persistent sleep disruption, especially alongside daytime fatigue or other symptoms, is worth discussing with a physician, since these can sometimes signal an underlying sleep disorder.