Primer of Useful Sleep Terms

Using standard sleep terms can help clarify what is really going on with your sleep.  Here are some terms that we use in the field, and which are sometimes confusing to people or misunderstood.   Having clarity will help diagnose any sleep problems you’re having.

Bedtime – This is the time that you get into bed with the intention of sleeping.  This should be the same time as ‘Lights Out.’  This should not be the time you got into bed to read, watch TV, or talk with your bedpartner.

Waketime – This is the time you awaken for the day, as distinct from the time you get out of bed, which may be later.

Sleep Onset – The number of minutes it took to fall asleep after Lights Out. 

Wakenings after sleep onset – The number of times you awoke between Lights Out and your Wake Time.  You can also record the amount of Wake Time After Sleep Onset.

Total Sleep Time – The amount of time between Bedtime and Waketime, minus Sleep Onset and Wake Time After Sleep Onset.

Time in Bed – The amount of time between Bedtime and Waketime.

Sleep Efficiency:  The Total Sleep Time divided by Time in Bed.  Should be > 90%.

Here’s an example:  Last night Alice read in bed starting at 9:30pm.  At 10pm she turned off the light, and was asleep in 15 minutes.  She woke up once to use the bathroom and was back asleep in 15 minutes.  At 7:30am her alarm went off.  She lay awake in bed for another 30 minutes doing her meditation before getting up at 8am.

Bedtime =10pm,  Waketime =7:30am,  Sleep Onset =15 minutes, Wakenings after sleep onset =1, Wake time after sleep onset =15minutes, Total sleep time =9 hours (10pm to 7:30am minus 15 minutes sleep onset and minus 15 minutes wake time after sleep onset), Time in Bed = 9.5 hours, Sleep Efficiency = 94% (9/9.5)

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