Sleep calculator for midpoint and timing drift.
Enter sleep onset and wake time to find the centre of your sleep window, then see how daygauge compares Apple Health sleep timing with your baseline.
How do you calculate sleep midpoint?
Sleep midpoint is halfway between sleep onset and wake time. Sleep from 23:30 to 07:30 has a midpoint of 03:30.
Calculate your sleep midpoint.
Duration 8h 00m. This is the centre point between sleep onset and wake time.
daygauge uses this timing as baseline evidence. One night is a note, repeated drift becomes a weekly recap pattern.
How to calculate sleep midpoint
Take the time you fell asleep and the time you woke up, then find the halfway point between them. If the sleep window crosses midnight, count the full window first.
Example: 00:20 to 07:40 is 7 hours 20 minutes of sleep. Half of that is 3 hours 40 minutes. Add it to 00:20 and the midpoint is 04:00.
Why the number matters less than the comparison
A single midpoint only gives a timestamp. The useful signal is how far it moved from your normal baseline.
daygauge would compare tonight with your last similar weekdays, then show whether the shift was unusual enough to affect your Life Index confidence or sleep-timing evidence.
What daygauge would show
Evidence: Sleep midpoint 04:00, 42 minutes later than your last 8 Tuesdays.
Next move: keep wake time within 30 minutes tomorrow and watch whether the midpoint comes back toward baseline.
How sleep midpoint becomes useful evidence.
The raw midpoint is only one signal. daygauge would combine it with sleep duration, wake-time variation, movement timing and missing-data confidence before changing the Life Index.
Sleep midpoint 04:00 · 42 min later than your Tuesday baseline · medium confidence because one sleep sample is missing · -18 Life Index impact.
Sources daygauge can cite without overclaiming.
These sources inform product wording and evidence labels. They should not be turned into personal diagnosis, treatment or disease-risk prediction.
- Sleep regularity and mortality: UK Biobank analysis
- Nature Medicine 2024 wearable sleep study
- CDC sleep basics
Research context only. daygauge does not diagnose, treat, prevent or predict disease risk. Personal medical concerns belong with a qualified clinician.
Related daygauge guides.
Want daygauge to explain your Apple Health sleep against your baseline?
daygauge turns the same timing calculation into a daily sleep receipt, Life Index impact and weekly recap when the pattern repeats.
iOS TestFlight first · paid app, one plan · evidence context, not medical advice