The logic
Sleep pressure builds with every hour awake and discharges when you sleep. When you spend long hours in bed awake, you discharge a trickle of pressure continuously, so the pressure at bedtime is low — you lie down not really sleepy. Compressing the window concentrates the pressure: you go to bed genuinely sleepy, fall asleep quickly, and stay asleep.
The cost is real: for the first one to two weeks you sleep less than before. The benefit arrives after that, and it is durable.
Step 1 — Establish your baseline (one to two weeks)
Keep a sleep diary. Each morning record:
- Time you got into bed
- Time you estimate you fell asleep
- Number and approximate duration of awakenings
- Time you got out of bed
Calculate average total sleep time across the week. Be conservative — round down.
Step 2 — Set the window
Time in bed = average total sleep time + 30 minutes, with a floor of 5.5 hours. If your average sleep is 5 hours 45 minutes, your window is 6 hours 15 minutes.
Pick a fixed wake time you can hold seven days a week, and count backwards to get your bedtime. If you wake at 7:00 and your window is 6h15m, bedtime is 00:45.
Do not go below 5.5 hours, and do not extend the window during the week to compensate for a bad night.
Step 3 — Adjust weekly by sleep efficiency
Sleep efficiency = (total sleep time ÷ time in bed) × 100.
- Above 90%: add 15 minutes to time in bed next week.
- Between 85% and 90%: keep the window unchanged.
- Below 85%: reduce time in bed by 15 minutes next week.
Repeat weekly. Most people reach a stable, efficient window within four to six weeks.
Rules that make or break it
- Fixed wake time, every day. This is non-negotiable and anchors everything.
- No naps. A nap discharges the pressure you are trying to build.
- No going to bed early to catch up. The window is the window.
- Temporary sleepiness is expected. Plan for it.
What week one feels like
Tired, often irritable, occasionally foggy. Some people feel better than expected because the sleep they do get is more continuous. If you drive professionally or operate machinery, speak to a clinician first, and consider starting during a quieter period.
Who should not do this without supervision
- Bipolar disorder — sleep deprivation can trigger mania.
- Uncontrolled epilepsy.
- Untreated or suspected sleep apnoea.
- Shift workers on a rotating schedule.
- Pregnancy, or anyone for whom daytime sleepiness creates a safety risk.
If any of these apply, get assessed rather than self-treating.
Supporting it with body work
Sleep restriction makes you sleepy; it does not lower arousal. If you arrive at your new later bedtime wired and tight, you will still take a long time to fall asleep. Pair it with Feldenkrais movement, progressive muscle relaxation, or extended-exhale breathing in the last half hour before bed.