Habits
Sleep Efficiency Calculator
Sleep efficiency is the share of time in bed spent asleep. It is a standard measure in sleep diaries, sleep studies and cognitive behavioral therapy for insomnia (CBT-I). Enter when you got into bed, when you got out, how long it took to fall asleep and how long you were awake during the night.
How it works
Time in bed = out of bed time minus into bed time (wrapping past midnight). Time asleep = time in bed minus minutes to fall asleep minus minutes awake during the night. Sleep efficiency = time asleep / time in bed x 100.
Example
In bed 10:30 PM to 6:30 AM is 8 h. 30 minutes to fall asleep plus 45 minutes awake = 75 minutes, so time asleep is 6 h 45 min. Efficiency = 6.75 / 8 x 100 = 84.4 percent.
Assumptions and limits
- Estimates of time awake are subjective; people with insomnia often overestimate it and a diary averaged over 1 to 2 weeks is more useful than a single night.
- The 85 percent figure is a commonly used target in sleep restriction therapy; some programs use 80 or 90 percent, and these bands are general guidance, not diagnostic cutoffs.
- Time after the final awakening that you spend lying in bed counts as awake time; add it to the awake minutes.
- This is a screening and education aid, not a diagnosis. Only a clinician, usually with a sleep test, can diagnose a sleep disorder.
Frequently asked questions
What is a normal sleep efficiency?
Healthy adult sleepers often have sleep efficiency of 85 percent or more. It tends to decline somewhat with age. Values persistently below that, together with daytime effects, are common in insomnia.
How is sleep efficiency used in CBT-I?
In sleep restriction therapy, a clinician sets a time in bed window close to your actual sleep time, then widens it gradually when sleep efficiency stays high (often around 85 to 90 percent) and narrows it when it is low. This should be done with professional guidance, especially if you have bipolar disorder, seizures or a job where sleepiness is dangerous.
Is spending more time in bed a good way to sleep more?
Often not. Extra time in bed tends to add more awake time, which lowers efficiency and can strengthen the link between bed and wakefulness.
Sources
Tools and screening scores are general information. They cannot diagnose or rule out a sleep disorder. Read our medical disclaimer.