What changes sleep timing and regularity

When you sleep and how consistent it is from day to day.

Every page below says it can change this metric. Strongest evidence first. Each page's "Effect on your sleep score" section says how much and how sure we are.

How sleep worksTwo systems decide when you get sleepy and how deeply you sleep. Almost every tip on this site works through one of them.
- Evidence: Strong
- Low effort
- Free
- Works: 1 week
Sleep restrictionSpend less time in bed so the time you do spend is asleep. A core part of CBT-I, with clear rules and real side effects.
- Evidence: Strong
- High effort
- Free
- Works: 3–4 weeks
What "good sleep" meansEnough hours, falling asleep without a fight, few wake-ups, regular times, and feeling alert in the day.
- Evidence: Strong
- Low effort
- Free
- Works: 1 week
ChronotypeYour chronotype is how early or late your body clock runs. It's partly genetic and changes with age, but light can move it by an hour or two.
- Evidence: Some
- Low effort
- Free
- Works: 1–3 weeks
Consistent wake timeGet up at the same time every day, weekends included. It anchors your body clock and makes falling asleep easier.
- Evidence: Some
- Medium effort
- Free
- Works: 1–2 weeks
Darkness and eye masksMake the bedroom as dark as you can, with blackout curtains or an eye mask. Experts recommend under 1 lux at the eye while you sleep.
- Evidence: Some
- Low effort
- Low cost
- Works: tonight
Jet lagJet lag is your body clock running on home time after you fly. Timed light, a shifted sleep schedule and, where allowed, melatonin can cut it short.
- Evidence: Some
- Medium effort
- Low cost
- Works: 2–7 days
MelatoninMelatonin is better at shifting your body clock than at knocking you out. For sleep onset it saves about 7 minutes on average. Low doses work; labels are often wrong.
- Evidence: Some
- Low effort
- Low cost
- Works: 1–3 days for timing shifts
Morning lightGet outside in daylight soon after you wake up. It sets your body clock earlier, so you get sleepy at a sensible time.
- Evidence: Some
- Low effort
- Free
- Works: 1–2 weeks
Screens and blue lightThe light from your phone matters less than you've heard. What you do on it, and how late it keeps you up, matters more. Dim the room, and put the phone down when you're sleepy.
- Evidence: Some
- Medium effort
- Free
- Works: tonight
Social jet lagSocial jet lag is the gap between when you sleep on workdays and on days off. Shrink it by keeping your wake time steady and getting morning light.
- Evidence: Some
- Medium effort
- Free
- Works: 1–2 weeks
What sleep scores measureWhat goes into the sleep and readiness scores from Oura, WHOOP, Apple Watch and Garmin, according to each company's own documentation.
- Evidence: Some
- Low effort
- Free
- Works: today
Which habits change which metricA table of common sleep habits against the numbers your wearable shows, with the direction of each effect, how sure the research is, and where nobody has looked.
- Evidence: Some
- Low effort
- Free
- Works: tonight to 2 weeks
Sharing a bedSharing a bed with a partner or pet has pluses and minuses, and the research is thin. Separate duvets, earplugs and a dog off the bed are easy fixes to try.
- Evidence: Weak
- Low effort
- Low cost
- Works: tonight
Wind-down routineGive yourself 30–60 minutes of dim, quiet, low-effort time before bed. A few parts are tested; most of it is sensible rather than proven.
- Evidence: Weak
- Low effort
- Free
- Works: 1–2 weeks