Non-24-Hour Sleep-Wake Disorder¶
Non-24 is a circadian rhythm sleep-wake disorder in which a person's internal clock is not entrained to the 24-hour day. The sleep-wake cycle runs longer (or, rarely, shorter) than 24 hours, so sleep timing drifts later each day, cycling around the clock over weeks.
It is common in people who are totally blind (with no light perception, the strongest zeitgeber cannot entrain the clock), and it also occurs in sighted people.
Not medical advice
Diagnosis and treatment of Non-24 belong with a qualified clinician. This page is a community overview, not a substitute for medical care.
In this section¶
-
Diagnosis
How clinicians identify Non-24, and how to prepare.
-
Treatment
Light, dark, melatonin, medication — and a realistic view.
-
Research
Mechanisms, measurement, and where the science is heading.
-
Recognising your pattern
What the drift looks like on a chart, and living with it.
Common features¶
- Sleep onset and wake time that shift progressively later (or earlier) over days to weeks.
- Alternating "good" and "bad" stretches as the rhythm cycles in and out of phase with the desired schedule — periods of daytime sleepiness and night-time wakefulness in between.
- Difficulty holding a fixed social, school, or work schedule.
Seeing the drift¶
Because the hallmark is drift, a long, continuous record of sleep timing is the clearest way to see the pattern. The Zeitlog tracker charts sleep over time, so a free-running rhythm shows up as a diagonal band marching across the chart.
Track your sleep with Zeitlog Find a specialist
See also¶
- Non-24 subreddit (r/N24)
- Overview and treatment options for Non-24
- VLiDACMel entrainment therapy
- Trouble sticking to a bedtime
Contributions welcome
Lived-experience notes, treatment overviews (with sources), and clinician-reviewed content are all welcome — contribute here.