How to use Sleep Diary
- Enter start and end timestamps with explicit UTC offsets, followed by main or nap, awakening count and awake minutes.
- Check elapsed time and the subtraction of awake minutes. Main sessions starting before 18:00 are grouped under the previous evening; naps use their start date.
- Download CSV for rows, JSON to continue editing later, or PDF for a printable copy. Review exports before sharing them.
Example: Sleep Diary
Subtract twelve awake minutes from a main sleep interval.
Options
- Session grouping
- The evening grouping is a report convention. It does not identify a biological night or select a sleep target.
- Awake minutes
- Only the entered minutes reduce the interval. Awakening count is reported separately; overlapping sessions are refused.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
Elapsed time comes from explicit offsets
Start and end timestamps include their UTC offsets. This makes elapsed time independent of the browser location and allows an offset change across daylight-saving transitions. Awake minutes are subtracted from the interval; awakening counts are reported separately. The result is an entered record, not a sleep-quality score or diagnosis.
Questions about Sleep Diary
Does it recommend how long to sleep?
No. It totals the sessions and awake minutes you enter. It does not select a sleep target or judge sleep quality.
What if the clocks changed overnight?
Enter the offset in force at each endpoint. The tool uses the two actual instants and does not guess a time-zone transition.
Can sessions overlap?
Overlapping intervals are refused so the same time cannot be counted twice. Correct the timestamps or split the record into separate nonoverlapping sessions.