Sleep restriction

Spend 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

Why it matters

People who sleep badly often spend extra time in bed to make up for it. That backfires: the extra hours are spent awake, the bed becomes linked with being awake, and the drive to sleep weakens [3].

Sleep restriction does the opposite. The AASM describes it as limiting time in bed to your average sleep, which builds sleep drive, then adjusting it up or down based on sleep efficiency until you’re sleeping enough [1].

This page is for healthy people with mild trouble. If you’ve had trouble sleeping at least 3 nights a week for more than 3 months, that fits the definition of chronic insomnia [3]. The first-line treatment is CBT-I, in person or digital [7].

How to do it

1. Keep a sleep diary for 1 week. Each morning, note when you got into bed, roughly when you fell asleep, time awake in the night, and when you got up. The sleep diary tool does the maths.
2. Work out your average total sleep. That’s your starting sleep window, the time you allow yourself in bed. If it comes out under 5 hours, use 5 hours [2].
3. Fix your wake time first. Pick one you can keep every day, weekends included, and count back to get your earliest bedtime. Example: 6 hours 15 minutes average sleep and a 6:45 a.m. alarm means bed no earlier than 12:30 a.m.
4. Only go to bed at that time if you’re sleepy. If you can’t sleep after about 20 minutes, get up and do something relaxing until you’re sleepy [3].
5. No naps, and no lying in, however tired you feel.
6. Each week, check your sleep efficiency: total sleep divided by time in bed, times 100. Then adjust your window [2]:
   • 90% or more: add 15 minutes (go to bed 15 minutes earlier).
   • 85–89%: keep the same window.
   • Under 85%: take away 15 minutes, but never go below 5 hours.
7. Stop extending once you feel rested in the day.

The sleep diary tool uses these rules to suggest your window.

Common mistakes

• Shifting the wake time. Move the bedtime, not the alarm. See consistent wake time.
• Driving while drowsy. In a small study, reactions stayed slower than normal for weeks [2].
• Quitting early. In that study, sleep loss was biggest on the first night, and sleepiness was back to normal by 3 months [2].
• Carrying on alone when it isn’t working. If sleep hasn’t improved after 4 weeks, get a full course of CBT-I [3].

Effect on your sleep score

• Efficiency, time to fall asleep, wake-ups: in a meta-analysis of 8 trials, all improved by large amounts, measured by sleep diary [4].
• Total sleep: expect it to drop at first. In 16 people with insomnia, lab-measured sleep fell by 91 minutes on the first night and was still 69 minutes lower after three weeks [2]. By the end of treatment, trials found no change on average [4].
• Deep sleep, REM, HRV, resting heart rate: we found no study measuring these in healthy adults with wearables.

How confident: high for efficiency in people with insomnia; low for healthy people with mild trouble.

Evidence

Rated Strong, for people with insomnia. The AASM guideline suggests sleep restriction as a stand-alone treatment (a conditional recommendation) and strongly recommends full CBT-I, which includes it [1]. A 2021 meta-analysis of 8 randomized trials found large improvements in insomnia severity, but 6 of the 8 trials had a high risk of bias and few had long-term follow-up [4]. In the largest trial, 642 adults in English general practices got four nurse-led sessions of sleep restriction or a sleep hygiene booklet; at 6 months the sleep restriction group had lower insomnia scores [5]. The method dates from a 1987 study of 35 people with long-standing insomnia [6].

Limits: almost all of this is in people diagnosed with insomnia, not healthy sleepers. Side effects are real: more daytime sleepiness and trouble concentrating early on [1][2]. Trials use different window rules; ours come from one well-described protocol [2].

General information for healthy adults, not medical advice. If you have a sleep problem that lasts, read when to see a doctor. Sources checked 4 October 2026. Spot a mistake? Tell us.