How the sleep window works
The sleep window is sleep restriction, one of the core parts of CBT-I, described by Arthur Spielman and colleagues in 1987. The name sounds harsh. The idea is simple. Spend only as long in bed as you’re actually sleeping right now, and let that time grow as sleep fills it.
Why less time in bed
When nights are broken, most people spend longer in bed to make up for it. Seven hours of sleep spread over nine hours in bed means two hours of lying awake, often in pieces through the night. Shrinking the time in bed is meant to build sleep drive, so sleep tends to come faster and hold together better. Over the weeks, the window grows back.
How the window is set
- A baseline from your diary. The window opens after 7 complete nights. Two weeks gives a steadier average.
- Your wake time. You pick one time to get up every day, weekends included. This is the anchor.
- The length. Your time in bed starts at your average total sleep from the diary, never less than 5 hours and 30 minutes in bed.
- Bedtime. Your wake time minus the window. Go to bed no earlier than that, and only when you’re sleepy. Later is fine.
Each week
The sleep window check looks at your efficiency for the week, which is the share of your time in bed you spent asleep, and suggests a change.
- 90% or higher. Bedtime 15 minutes earlier.
- 85 to 89%. No change.
- Under 85%. Bedtime 15 minutes later, never less than 5 hours and 30 minutes in bed.
A week with fewer than 5 complete nights gets no suggestion, because a few nights can swing the average a lot. If you spent most nights in bed outside your window, the check says so and keeps the window where it is, since the numbers then show something other than the window. You always decide. Neither the app nor the calculator moves the window on its own.
The window keeps growing until efficiency stays under 85% at the longer length, or until you feel rested during the day. Then you can keep it where it is.
These thresholds are the ones taught in most treatment manuals. Clinicians sometimes adjust them, for example moving bedtime earlier at 85% for older adults. If you work with one, follow their plan.
Why the first weeks are hard
Expect to feel sleepier during the day at first, sometimes much sleepier. Studies that measured this found real drops in alertness in the early weeks, which usually ease as the window grows. Plan the start for a calmer stretch. Don’t drive or do anything risky when you feel drowsy.
The pull to go to bed early or sleep in on a bad day is strong. Holding the window, especially the wake time, matters more than anything else in the method.
Sleep compression
Sleep compression gets to the same place more gently. Your time in bed starts 30 minutes shorter than it is now. After that, in any week your efficiency is under 85%, it shrinks by up to 30 more minutes, never below how much you sleep now. It’s often preferred for older adults and for anyone who can’t safely be very sleepy.
When not to use it alone
Talk with a health care provider first if you have bipolar disorder, a seizure disorder, sleep apnea, sleepwalking or other unusual behavior during sleep, a history of falls, or another health problem, if you take medicine that makes you drowsy, if you’re pregnant, or if you drive or use machinery for work. The window also isn’t built for rotating shifts.
Stop the window and talk with a health care provider if you nod off during the day without meaning to, have a seizure or a fall, or notice your mood running unusually high, your thoughts racing, or that you need much less sleep than usual. If you already doze off easily during the day, see a doctor before you start.
References
- Spielman, A. J., Saskin, P., & Thorpy, M. J. (1987). Treatment of chronic insomnia by restriction of time in bed. Sleep, 10(1), 45–56. doi.org/10.1093/sleep/10.1.45
- Miller, C. B., Espie, C. A., Epstein, D. R., et al. (2014). The evidence base of sleep restriction therapy for treating insomnia disorder. Sleep Medicine Reviews, 18(5), 415–424. doi.org/10.1016/j.smrv.2014.01.006
- Kyle, S. D., Miller, C. B., Rogers, Z., et al. (2014). Sleep restriction therapy for insomnia is associated with reduced objective total sleep time, increased daytime somnolence, and objectively impaired vigilance: Implications for the clinical management of insomnia disorder. Sleep, 37(2), 229–237. doi.org/10.5665/sleep.3386
- Lichstein, K. L., Riedel, B. W., Wilson, N. M., Lester, K. W., & Aguillard, R. N. (2001). Relaxation and sleep compression for late-life insomnia: A placebo-controlled trial. Journal of Consulting and Clinical Psychology, 69(2), 227–239. doi.org/10.1037/0022-006X.69.2.227
Helpful links
Everyday Insight’s tools are for education and personal reflection. They are not therapy or medical care, and they are not for emergencies. In an emergency, call 911. If you are in crisis in the United States, call or text 988.