Keeping a sleep and wake-time diary as a plain observation record

Goal

Keep a record of when you went to bed, when you think you fell asleep, when you woke and when you got up, written the same way every day, so that the series can be looked at later without relying on memory. The diary is an observation log; it diagnoses nothing and recommends nothing.

Prerequisites

A fixed place for the diary (paper beside the bed or a note on the phone), a fixed moment for filling it in (within an hour of getting up), and a decision on formats: 24-hour clock times, durations in minutes.

Steps

1. Header once: the time zone as an IANA name such as Europe/Zurich, the clock or device used, and whether the entries are estimates. They are, unless a device records them; say which fields come from a device.
2. Every morning, write the previous night under the evening's date: time lights went out, estimated minutes to fall asleep, number of remembered awakenings with their estimated total minutes, final wake time, time out of bed. Mark an unknown field with a dash rather than a guess.
3. Every evening, write the day: naps (start, minutes), caffeine or alcohol with clock time, exercise (time, minutes), and unusual events such as travel, illness, late screen work or noise. Keep to facts you would state the same way twice.
4. Note clock changes and travel explicitly. The IANA Time Zone Database records changes to time zone boundaries, UTC offsets and daylight-saving rules by location; on a night when a change applies, state which offset the clock times use, otherwise a one-hour jump appears in the series for no reason.
5. Weekly, copy the entries into a table with one row per night and compute time in bed and estimated sleep as arithmetic from the fields; leave the diary itself unedited.
6. When looking back, compare weeks on the same fields only. A change in wording or in the moment of filling in starts a new series.

Expected result

A consistent, dated series of self-reported times with the estimates and recording conditions stated, which you can read yourself or show to a person of your choosing.

Limits and test basis

Proposed format; no finding about sleep and no recommendation follows from it. Self-reported times are estimates; a wearable's figures are a different measurement with its own unstated error, and the diary claims neither is right. If the reason for keeping the diary is a health concern, that is a matter for a professional, not for this protocol.