LodestarEight hours in bed and a disappointing sleep score is a common and frustrating combination. The reason is almost always that a sleep score measures more than time.
What a sleep score looks at
Fitbit's own sleep score combines three things: how long you slept, the quality of that sleep (mostly deep and REM sleep), and restoration, which looks at your heart rate while you slept and how restless you were. A full night can still score poorly on the last two.
Common reasons for a low score after a long night
- Time in bed isn't time asleep. Twenty minutes to fall asleep plus a few long wake-ups can quietly take an hour off a "full" night.
- Less deep sleep. Alcohol, a late workout, a warm room or a late meal can all cut into deep sleep, which mostly happens in the first half of the night.
- Less REM sleep. REM comes mostly in the last part of the night, so an early alarm cuts it short even if you went to bed early. Alcohol also suppresses it.
- A higher heart rate while asleep. If your sleeping heart rate stays above your resting rate, the night counts as less restorative, even if you didn't wake up. What raises it.
- Lots of brief wake-ups. You may not remember them, but they fragment the night.
What helps
- Keep a similar bedtime and wake time, including weekends. In one study, students with irregular sleep had later body clocks and did worse during the day than regular sleepers, even with similar total sleep (Phillips and colleagues, Scientific Reports, 2017).
- Give alcohol and big meals a few hours before bed.
- Keep the bedroom cool and dark.
- If you're short on sleep, extra sleep over the next few nights helps more than one long lie-in. More on sleep debt.
How Lodestar shows it
Lodestar's Sleep score shows exactly which part of the night cost you points: duration against what you need, deep sleep, REM, and efficiency. It also tracks how regular your sleep is and how much sleep debt you're carrying, and plans tonight's sleep around it. Everything is worked out on your iPhone.