About the Sleep Efficiency Calculator
Sleep efficiency is the percentage of your time in bed that you actually spend asleep. It is one of the core numbers sleep clinicians look at in a sleep diary, because lying awake in bed for long stretches is a hallmark of insomnia even when total sleep time looks acceptable. A healthy adult typically sleeps for 85% or more of the time they spend in bed.
Enter when you got into bed, when you finally got up, how long it took to fall asleep, how many minutes you were awake during the night, and any time you lay awake after your final awakening. The calculator returns your total sleep time, time in bed, sleep efficiency and a rating, plus the starting "sleep window" that cognitive behavioural therapy for insomnia (CBT-I) would use.
Sleep efficiency is most useful as an average over one to two weeks of sleep-diary entries rather than a single night. The sleep-window suggestion is educational: sleep restriction therapy can cause daytime sleepiness and is best done with a clinician, and it is not advised for people with bipolar disorder, epilepsy, untreated sleep apnoea or jobs where drowsiness is dangerous.
With the default inputs, the sleep efficiency is 87.5%. Change any value above to recalculate instantly.
How to use the sleep efficiency calculator
- 1Enter the time you got into bed and the time you got out of bed.
- 2Estimate how many minutes it took you to fall asleep.
- 3Add up the minutes you were awake during the night and enter the total.
- 4Enter any time you lay awake in bed after your final awakening.
- 5Read your sleep efficiency and rating; repeat for 1–2 weeks and average the results.
Formula and method
Time in bed (TIB) runs from the moment you get into bed to the moment you get up, crossing midnight if needed. Total sleep time (TST) is time in bed minus the minutes it took to fall asleep (sleep onset latency, SOL), minutes awake after sleep onset (WASO) and minutes lying awake after the final awakening (early morning awakening, EMA). Sleep efficiency (SE) is TST as a percentage of TIB.
The CBT-I sleep window follows standard sleep restriction practice: start with a time in bed equal to your average total sleep time, rounded here to the nearest 15 minutes and never shorter than 5 hours. Each week, extend it by 15 minutes if efficiency is 90% or higher, keep it if efficiency is 85–89%, and shorten it by 15 minutes if efficiency is below 85%.
- SE
- Sleep efficiency (%)
- TST
- Total sleep time
- TIB
- Time in bed, from getting into bed to getting up
- SOL
- Sleep onset latency (minutes to fall asleep)
- WASO
- Wake after sleep onset (minutes awake during the night)
- EMA
- Minutes awake in bed after the final awakening
Worked examples
Typical night: 11 pm to 7 am
Eight hours (480 minutes) in bed minus 20 + 30 + 10 = 60 minutes awake leaves 420 minutes, or 7 hours, of sleep. 420 ÷ 480 = 87.5%, inside the healthy 85%+ range, and the CBT-I window would start at 7 hours.
Insomnia pattern with long awakenings
Time in bed is again 8 hours, but 45 + 60 + 30 = 135 minutes are spent awake, leaving 345 minutes (5 h 45 min) of sleep. Efficiency is 345 ÷ 480 = 71.9%. Sleep restriction would start with a 5 h 45 min window to consolidate sleep.
Short latency, late bedtime
Seven and a half hours (450 minutes) in bed with only 25 minutes awake gives 425 minutes asleep. 425 ÷ 450 = 94.4%. Rounded to the nearest 15 minutes, the sleep window would be 7 hours, and CBT-I would extend it because efficiency is above 90%.
Frequently asked questions
What is a good sleep efficiency?+
For adults, a sleep efficiency of 85% or higher is generally considered normal, and 90% or more is very good. Values consistently below 85% are common in insomnia and are a target in cognitive behavioural therapy for insomnia.
How is sleep efficiency calculated?+
Divide total sleep time by total time in bed and multiply by 100. For example, 6.5 hours asleep during 8 hours in bed gives 6.5 ÷ 8 × 100 = 81.3%. Time in bed includes the time it takes to fall asleep and any time awake.
Is 100% sleep efficiency good?+
Not necessarily. Falling asleep instantly every night and never waking can be a sign of significant sleep deprivation. Most well-rested people take 10–20 minutes to fall asleep and have brief awakenings, so efficiency in the high 80s to mid 90s is typical.
What is the CBT-I sleep window?+
In sleep restriction therapy, time in bed is temporarily limited to roughly your average sleep time (at least 5 hours) to build sleep pressure and consolidate sleep. The window is then lengthened by about 15 minutes each week while efficiency stays at 85–90% or above.
Should I use a sleep tracker or a diary?+
Both work. Wearables estimate sleep from movement and heart rate and can misjudge quiet wakefulness as sleep, which inflates efficiency. Clinical CBT-I programmes usually rely on a daily sleep diary, averaged over one to two weeks.
Does napping affect sleep efficiency?+
Sleep efficiency is normally calculated for the main night-time sleep period only. Long or late naps can, however, reduce sleep pressure and lower your night-time efficiency, so CBT-I usually advises avoiding naps during sleep restriction.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.