Time in bed doesn’t equal time asleep.
Just because you’ve been in bed for 7 hours doesn’t mean you slept for 7 hours. It’s more likely that you slept 6.
Based on my Oura Ring, my own difference is 30 to 60 minutes per night.
This led me to the following rule:
Allow a 1 hour margin of safety
If you want to sleep for 8 hours, go to bed exactly 9 hours before that:
- If you get up at 6.00 am, go to bed at 9.00 pm
- If you get up at 7.00 am, go to bed at 10.00 pm
- If you get up at 8.00 am, go to bed at 11.00 pm
For a long time, I didn’t see this clearly, which blurred my view of when to go to bed.
Now, I’ve put my exact bed time on my calender, based on the alarm of the following day.
Clear and simple.