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Bedtime consistency

How much the time you fall asleep wobbles from night to night over the last week. A smaller spread means steadier timing.

Pajdo takes the start of your main sleep on each of the last 7 nights in Apple Health and works out the standard deviation: roughly how far a typical night sits from your average bedtime. He needs at least 2 nights, and naps don't count.

Sleep timing seems to matter alongside sleep length. In about 61,000 UK Biobank adults who wore wrist sensors for a week, more regular sleep and wake timing went with longer lives on average, and predicted that better than sleep duration did. The CDC lists going to bed and getting up at the same time every day as a healthy sleep habit.

When the spread tops 90 minutes across at least 5 nights, Pajdo mentions it. In a US study of about 2,000 older adults, above 90 minutes was the only band that clearly stood apart from the steadiest sleepers.

What tends to push it up

  • Late nights or sleeping in on some days
  • Travel across time zones
  • Shifts that change your sleep times

What tends to pull it down

  • Going to bed at a similar time each night

Worth a try

Keep your sleep times steady

The NHS says going to bed and getting up at similar times each day makes it easier to fall asleep. The American Academy of Sleep Medicine suggests getting up at the same time every day, even on weekends. A National Sleep Foundation expert panel agreed that regular sleep timing matters for health and performance.

Pajdo's bedtime consistency shows how much your bedtime has moved around over the last week, using sleep from Apple Health.

Try it: pick a wake-up time you can keep all week, set an alarm, and let bedtime settle around it.

Give your evening a slow finish

The NHS says a calm bedtime routine can help you prepare for sleep, and suggests reading, breathing exercises or calming music. The American Academy of Sleep Medicine recommends a relaxing routine and limiting bright light in the evening. The National Sleep Foundation suggests dimming the lights as bedtime gets closer.

Try it: pick a wind-down start time before your usual bedtime. Dim the lights, put your phone to bed somewhere out of reach, and do the same calm thing each night so it becomes a cue.

Sources

  1. Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study, Sleep (Windred et al., 2024)
  2. Sleep irregularity and risk of cardiovascular events: the Multi-Ethnic Study of Atherosclerosis, Journal of the American College of Cardiology (Huang et al., 2020)
  3. About sleep, Centers for Disease Control and Prevention
  4. How to fall asleep faster and sleep better, NHS Every Mind Matters
  5. Healthy Sleep Habits, American Academy of Sleep Medicine
  6. The importance of sleep regularity: a consensus statement of the National Sleep Foundation (Sletten et al. 2023), Sleep Health
  7. How to Make a Sleep-Friendly Bedroom, National Sleep Foundation

Checked against these sources on September 15, 2026.

This is general wellness information, not medical advice. If a number worries you, or stays away from your usual for a while, talk to a doctor.

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