Sleep Efficiency Calculator

1. Pick one night or a diary week. A single night is a quick check. For a sleep window, use the average of a one to two week sleep diary, which is how the method is described.
2. Enter time in bed and sleep. For one night, give bedtime and rise time (or minutes in bed), then either total sleep or the minutes it took to fall asleep and the minutes you were awake. For a week, list hours in bed and hours asleep for each night.
3. Read the result and the caution list. You get your efficiency, its band, a starting sleep window that ends at your rise time, and the weekly rule. Read who should not restrict sleep before you change anything.

Sleep efficiency is the percentage of time in bed that you actually spend asleep. If you are in bed for 8 hours and sleep for 6, your efficiency is 75%. The other 2 hours are time spent lying awake: getting to sleep, waking in the night or waking before the alarm.

The Sleep Foundation says doctors who treat insomnia typically aim for a sleep efficiency of at least 85%. It also notes that a healthy person usually takes 10 to 20 minutes to fall asleep, so a night with no awake time at all is not the goal. Efficiency is useful because it separates two different problems: not enough sleep, and too much time awake in bed. Someone who sleeps 6 hours in 6.5 hours of bed has a very different problem from someone who sleeps 6 hours in 9.

Divide total sleep by time in bed and multiply by 100. For a diary week, the Sleep Foundation divides the average sleep by the average time in bed.

If you do not know your total sleep, the tool estimates it as time in bed minus the minutes it took to fall asleep and minus the minutes you were awake in the night.

The weekly rule applies once you are already following a sleep window. Before that, the Sleep Foundation steps start sleep restriction only when efficiency is below 85%.

This is the example the Sleep Foundation uses. A diary shows an average of 6.5 hours of sleep and 9 hours in bed, with a rise time of 6:00 AM.

The rise time does not move. The window grows or shrinks at the bedtime end, 15 minutes at a time. If the same person averaged only 5 hours of sleep, the window would still be 6 hours, because the Sleep Foundation says to stay in bed for six hours when average sleep is below that.

Sleep restriction makes you sleepier at first. The AASM guideline lists daytime sleepiness and trouble concentrating as side effects that usually fade as time in bed is extended. For some people that early sleepiness is a real risk. The sources used here name these groups:

Whatever your situation, the Sleep Foundation advises talking to your doctor before you start. The AASM guideline describes sleep restriction as a treatment where the patient is monitored by a clinician. The safest route is a CBT-I program or a clinician trained in it. Do not drive or do safety-critical work while you feel sleepy during the first weeks.

Sleep restriction is one part of cognitive behavioral therapy for insomnia (CBT-I). The AASM 2021 guideline makes a strong recommendation for multicomponent CBT-I in adults with chronic insomnia, and a conditional recommendation for sleep restriction on its own. It describes time in bed as first limited to the average sleep duration, then increased or decreased based on sleep efficiency. NHLBI describes CBT-I as a 6- to 8-week treatment plan.

The Steps In Order

• Keep a sleep diary for one to two weeks.
• Set a window equal to your average sleep, at least 6 hours, with a fixed rise time.
• Get up when the alarm goes off and do not nap during the day.
• Each week, work out efficiency again and apply the 15-minute rule until you feel rested and are satisfied with your sleep.

The window is a temporary tool. It is meant to grow back as sleep becomes more solid. For the other parts of an insomnia plan, see these practical steps to beat insomnia.

Time Spent Awake In Bed

Long sleep onset, waking in the night and lying in bed after waking early all lower the number. Each extra 30 minutes awake in an 8 hour night costs about 6 points.

Going To Bed Before You Are Sleepy

Extra time in bed does not add sleep if you are not sleepy, so efficiency falls. This is the pattern sleep restriction targets.

Habits Around Sleep

Caffeine, alcohol, late exercise and a noisy or bright room can all add awake time. The sleep hygiene basics cover these. The AASM advises against using sleep hygiene as the only treatment for chronic insomnia, so treat it as support rather than the whole plan.

How You Measure It

A diary and a wearable can give different totals for the same night, which changes the percentage. Pick one method and stick with it for the whole week.

Use efficiency together with total sleep. A person who sleeps 5 hours in 5.3 hours of bed has excellent efficiency and still a short night.

Judging By One Night

Single nights vary a lot. The method uses a weekly average.

Cutting The Window Below 6 Hours

The Sleep Foundation sets 6 hours as the minimum time in bed. This tool will not plan a shorter window.

Moving The Rise Time

Sleeping in after a bad night undoes the schedule. Keep the rise time fixed and change only the bedtime.

Chasing 100%

Some awake time is normal. The target is at least 85%, not zero minutes awake. Watching the number too closely can feed sleep worry, as covered in sleep tracking and insomnia.

Napping During Restriction

The Sleep Foundation steps say not to nap during the day while following the window.

The arithmetic is exact for the numbers you enter. The result is only as good as your diary, and the window is a starting point, not a prescription.

For more tools on sleep timing and sleep need, visit the sleep calculators home page.

At least 85%. The Sleep Foundation says this is the level doctors who treat insomnia typically aim for.

It is below the 85% target, meaning about a quarter of your time in bed is spent awake. It is not a diagnosis, but if it happens most weeks it is worth discussing with a doctor.

The sources used here give one target, 85%, and no table by age. The same formula and target are used for every adult in this tool.

It starts at your average total sleep from a sleep diary. The Sleep Foundation says to use six hours instead if you average less than six.

A fixed rise time keeps the schedule stable. The window changes at the bedtime end, 15 minutes at a time.

Once a week, using that week of diary entries. The weekly result decides whether to add, hold or remove 15 minutes.

It is a multi-week process. NHLBI describes full CBT-I as a 6- to 8-week plan, and the Sleep Foundation says to repeat the weekly step until you feel well rested.

Talk to a doctor first. The AASM guideline names groups for whom it may be unsafe, including drivers and people prone to mania, and describes it as monitored by a clinician.

Often yes. Daytime sleepiness and poor concentration are common early on and usually ease as time in bed is extended.

It uses the same idea, but the device estimates sleep from movement or heart rate. Its totals can differ from a diary, so do not mix the two within one week.

• Edinger et al: Behavioral and psychological treatments for chronic insomnia disorder in adults, an AASM clinical practice guideline (J Clin Sleep Med, 2021; PMID 33164742) (CBT-I strong recommendation; sleep restriction conditional; window starts at average sleep; contraindicated groups; early sleepiness)
• Sleep Foundation: Sleep Restriction Therapy (diary method, six-hour minimum, 85 to 90% weekly rule with 15-minute steps, who should not try it)
• Sleep Foundation: Sleep Latency (sleep efficiency formula; at least 85% target; 10 to 20 min to fall asleep)
• NHLBI: Insomnia Treatment (CBT-I is a 6- to 8-week plan; sleep restriction sets a specific time in bed)