Sleep calculator for midpoint and timing drift.

How do you calculate sleep midpoint?

• How do you calculate sleep midpoint?
• What is my sleep midpoint if I sleep past midnight?
• What does a later sleep midpoint mean?
• How does daygauge use sleep timing?

Calculate your sleep midpoint.

daygauge shows your sleep timing against your usual window. One night is a note. Repeated drift is worth watching.

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 shows your sleep timing against your usual window, so you can see whether last night was unusual.

What daygauge shows

Example reading: sleep started 42 minutes later than your usual window.

Next move: keep your wake time within 30 minutes of usual tomorrow and see whether your timing comes back toward your usual window.

What sleep timing does and does not change.

Your Life Index uses your sleep minutes compared with your own average. Sleep midpoint and bedtime are not part of it. daygauge shows sleep timing against your usual window as context.

• Earlier than usual: shown against your usual window. It does not change the Life Index by itself.
• Later than usual: shows timing drift even when total hours look acceptable.
• Missing sleep data: the Life Index leaves out the sleep part and rebalances instead of inventing a figure.
• Repeated weekend shift: this is what social jet lag describes. It is a pattern, not a diagnosis.

Further reading.

These studies describe groups of people. They help explain the topic, but they cannot tell you what will happen to you.

• eLife 2023 UK Biobank sleep regularity and mortality study
• 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.

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