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What does my Withings sleep-mat data look like?

368 nights on a sleep mat under the mattress: how much there is, what is typical, how it has moved, and where the last month sits.

Client name: George · Withings sleep mat · 2025-07-26 → 2026-09-29

Breaks of three nights or more with no night on the mat: 2025-12-30 → 2026-01-03 (5 nights); 2026-05-22 → 2026-05-24 (3 nights); 2026-06-16 → 2026-06-21 (6 nights); 2026-08-14 → 2026-08-16 (3 nights); 2026-09-09 → 2026-09-11 (3 nights). Single missing nights are not listed; there are 43.

Sleep

Each night is dated by the evening it began; a sleep starting before noon counts as the previous evening.

Stages and waking

Stages are the mat's own estimate from movement, breathing and heart rate under the mattress, not a sleep-lab recording.

Heart rate and snoring

Heart rate measured by the mat through the mattress, overnight.

By year

Median of the days that year; small number: days with a reading. Hover a cell for the middle half.

By day of the week

Median over every such day in the record. Bold: that measure's highest day; grey: its lowest. For night measures the day is the evening the night began, so "Fri" is Friday night.

Which device recorded each row

The export's sleep file mixes the mat and a Withings watch without saying which is which. Each row is matched to the device whose own raw recording lines up with it best; rows that match neither closely are 'unknown'. Only the mat's rows are on this page.

Body temperature readings

77 readings taken on purpose with a thermometer and stored in his Withings account (2017: 1, 2020: 16, 2021: 2, 2026: 58) — not the mat, and not the Apple Watch's wrist temperature. 12 fall on days he reported feeling ill. The highest is 37.2 °C; 3 are 37.0 °C or more and 0 are 37.5 °C or more. Fever is usually counted from 38.0 °C, so the highest reading is 0.8 °C short of it. Times are his local clock. Which device took them, and where on the body, is not in the export; normal ranges differ by site, so the band below is a common guide, not his own.

Questions this makes askable

• Do the colds he remembers show up on the mat? He recalls being ill on Jul 16–18, Aug 24–26, Sep 5–8, Sep 16–24, Sep 28–30 (2026). All fall inside the mat's record, so its heart rate, waking and breathing on those nights can be compared with his other nights — the check the Apple Watch illness detector still needs.
• Does restarting training tend to precede illness? The mat covers his trainer sessions, which began around the end of September 2025, so the question can be re-run with the mat's nights beside the Watch's.
• Do the mat and the Watch agree on a night? Two instruments, one quantity: a measurement-validity question, started by the alignment check below.

What the prose above is checked against

Each is computed at build time. One that fails stops the build rather than leave a sentence standing that the data no longer support.

• ✓ nights are dated by the evening they began: against his Apple Watch's sleep on 366 shared nights, time asleep correlates r = 0.91 on the same night and 0.10 / 0.15 one night either side; bedtime 0.92, against 0.19 / 0.16
• ✓ since the mat arrived (2025-07-26), 783 of 785 rows are attributed to a device; 2 unknown (limit 1%)
• ✓ no heart rate of 0 is drawn: the export writes 0 for 'not measured'
• ✓ no night is counted twice: 17 duplicate mat row(s) of a night already on file were dropped, leaving 368 nights
• ✓ every headline measure has enough nights to judge 'lately' (8 of 8)
• ✓ every one of the 77 temperature readings is a body temperature (34-42 °C), so none is a mistyped or room reading: lowest 35.7, highest 37.2

Sources and derivation

• Withings Health Mate export, sent September 30, 2026. Read from three of its files: the nightly sleep summary and the mat's and watch's raw sleep recordings. Files that identify the owner, his notes, and anything with a location were not used.
• The mat's raw recordings are stamped in a different time zone from the sleep summary; rows are matched on the absolute moment, and every time on this page is the local clock time of the night.
• A night belongs to the evening it began. A row under 3 hours in bed is a nap and is left out. Where the export lists one night twice for the mat, it is counted once.
• A heart rate of 0 in the export means not measured, and is left blank.
• Body temperatures come from the export's temperature file, a fourth file read for that table alone. Its times carry no time zone; they are taken as his local clock because, when checked on October 5, 2026, every weigh-in in the same export matched Apple Health's copy of it, stamped with his local offset, to the second.
• Every value on this page is in tidy.csv beside it.