Circadian Alignment Score: Understanding Sleep Timing and Regularity
Understand My Bio Age’s Circadian Alignment score, its sleep and activity inputs, and why it is not a direct test of your internal body clock.
By My Bio Age
Your Circadian Alignment score summarises patterns in recorded sleep and activity. It helps you review the regularity of your routine, but it does not directly measure melatonin timing or diagnose a circadian rhythm disorder.
What the app looks at
My Bio Age considers up to 30 days of available records and needs at least seven nights of usable sleep information. The calculation considers sleep timing regularity, differences between weekday and weekend sleep midpoints, timing patterns in heart rate and HRV, and the relationship between activity and sleep.
A sleep midpoint is halfway between sleep onset and waking. Comparing these points across nights offers a way to describe timing variation. It does not establish the timing of your internal biological clock.
Reading the score
- 75 to 100 is the app’s higher, green band.
- 50 to below 75 is the middle, yellow band.
- Below 50 is the lower, red band.
The bands are a guide to this app’s model, not medical reference ranges. Travel, shift work, caregiving and missing sleep records can affect interpretation. A score should not label one sleep schedule as universally right for everyone.
Build a more useful comparison
Before changing a routine, check whether Apple Health has complete sleep records and whether the same device is supplying them. If a tracker missed half a night, a change in timing may reflect the record rather than your sleep.
For general sleep habits, the National Heart, Lung, and Blood Institute recommends a regular sleep schedule and a quiet, dark sleeping environment. Shift workers may need an approach suited to their working hours.
Where to find more context
Open the Circadian Alignment detail view to compare available trends. In AI Coach, choose a Status, Why or Improve question about this metric. The answer is based on selected facts and can help you review a pattern, but cannot determine the cause of a sleep problem.
Circadian Alignment is separate from the weekly MyBioAge Index™. Sleep Regularity is an Index input; the Circadian Alignment score itself is not. Use both as wellness context, and discuss persistent sleep difficulties with a qualified professional.
For a practical review of the sleep records behind these patterns, read the Apple Watch sleep consistency guide.
Bring your sleep timing and daily Circadian Alignment into the same review. Download My Bio Age free on the App Store. The iPhone app is completely free, with no in-app purchases, subscription or account required. Health analysis stays on your iPhone, and the optional AI Coach runs fully on device after a model download.