Actual Sleep vs Time Spent Sleeping

By Andr.V.S. (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons

All Time Sleeping Average: (Target) 7h30m / day (Actual) 7h34m / day (149 night average)

3 Day Sleeping Average: (Target) 7+h / day (Actual) 8h17m / day (6h11m, 12h25m, 6h15m)

One interesting thing about Fitbit is it only records the actual sleep it feels you’ve had rather than the total time spent in bed.

Which to a certain extent means, I may have to reconsider my sleeping targets.

Of the current 22 sleeps I’ve logged on Fitbit, my current sleeping efficiency is 92%.

The implications are twofold:

  • I’m not getting enough sleep. If my All Time Sleeping Average is 7h34m, the implied actual sleep is 6h58m, which is close to the minimum 7 hours Fitbit recommends but too close for comfort for various reasons [1].
  • I should set a target of 8 hours of actual sleep. To provide a margin of safety whilst not causing marginal returns due to pursuing lots of sleep, I should target the mid-point between 7 – 9 hours of sleep that Fitbit recommends. That implies that I need 8h42m of sleep based on a 92% sleep efficiency.

Which, if I’m going to wake up at 5:30 am tomorrow, should mean that I need to go to sleep now. I’m already 7 minutes behind schedule.


[1] My sleeping efficiency is 92% as of the past 22 sleeps, but that was before I regularly did cardiovascular exercise. There’s a probable chance I may have had worst sleeping efficiency before, which drags my actual sleep time even more. There may also be other unaccounted for reasons, such as short sleeps I never logged, or sleeps being longer because I forgot to turn off SleepCycle after being awake.


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