Sleep Tracking
A sleep diary is a short daily record of when you slept and how you felt. Two weeks is the usual length, and it takes about a minute each morning. Sleep clinicians still ask for one rather than app data, because it captures your experience of sleep, which is what treatment decisions actually rest on. […]
A sleep diary is a short daily record of when you slept and how you felt. Two weeks is the usual length, and it takes about a minute each morning. Sleep clinicians still ask for one rather than app data, because it captures your experience of sleep, which is what treatment decisions actually rest on.
It is a simple log, kept once a day, of the basic shape of your night and how the following day went.
It is not a stopwatch exercise. You are not trying to record exact times, and you should not be checking the clock in the night to get them. Estimates are the point. A clinician wants to know roughly what happened and what it felt like.
Structured versions exist. The Consensus Sleep Diary was developed by sleep researchers as a standardised format, and many clinics use it or something close to it. A plain notebook works too.
This surprises people who arrive with months of app data. There are three reasons.
It records the thing that matters. Insomnia is defined partly by distress and daytime impact, not only by hours. No wrist sensor can record that you lay awake feeling anxious, or that you struggled through the afternoon. You can.
It captures behaviour, not just output. What time you got into bed, how long you stayed there awake, whether you napped, what you drank. Those are the levers behavioural treatment actually pulls.
It is standardised enough to compare. Devices differ, algorithms change with updates, and stage estimates are unreliable. A diary means the same thing this week as last week.
There is one more reason worth naming. A diary asks how you felt. A tracker tells you how you slept. For anyone drifting toward anxiety about their data, that difference matters, and we cover it in our article on orthosomnia.
Fill it in shortly after waking, while the night is still fresh. It should take about a minute.
The gap between getting into bed and getting out of bed is one of the more revealing figures in the whole record, because it shows how much time you spend in bed not sleeping.
If the full list feels like too much to sustain, four lines will still be useful:
A short diary you actually keep beats a detailed one you abandon after four days.
Two weeks is the standard, and there is a reason for it.
One week misses the weekday to weekend pattern, which is often where the useful information sits. Sleep also varies enough night to night that a few days can mislead in either direction.
If you are keeping it for an appointment, aim for two full weeks beforehand, including both weekends. If you miss a day, leave it blank and carry on. A gap is not a failure and it does not invalidate the record.
Sleep diaries are a long-standing part of clinical practice, used in both assessment and treatment for insomnia.
They are the basis for behavioural approaches. Cognitive behavioural therapy for insomnia, which has the strongest evidence base of any approach studied for long-running insomnia, is generally guided by diary data rather than device data.
Their known limitation is that they are subjective. People tend to misjudge how long they took to fall asleep and how long they were awake, and that misjudgement is more pronounced in people with insomnia. Diaries and laboratory measurement do not agree perfectly.
That is a real limitation, and it does not undermine the point. Perceived sleep is itself clinically meaningful. If you consistently experience your nights as broken and unrefreshing, that experience is part of the problem to be treated, whatever a sensor recorded.
Diaries and devices are also not mutually exclusive. Bringing both, with the diary as the primary record, is entirely reasonable.
After two weeks, read it as a whole rather than night by night.
Things worth noticing:
That last one is often the most interesting. Many people find their rested rating tracks consistency of timing more closely than it tracks hours slept.
Take it with you to any appointment. Do not summarise it. Bring the actual record, because the details are the useful part.
A diary is a good preparation for a conversation, not a substitute for one.
Ask specifically about cognitive behavioural therapy for insomnia if the problem is long-running. Major guidelines place it ahead of medication as a first step.
Rough estimates are fine and are what clinicians expect. Precision is not the goal, and checking the clock in the night to achieve it will make your sleep worse.
Whichever you will keep up. Paper has one advantage: it cannot show you a score or a graph, so it will not turn into something to optimise. If you use an app, make sure you are entering your own answers rather than importing device data.
Leave them blank and continue. A record with gaps is still useful. Do not go back and fill them in from memory, because that adds guesswork rather than information.
No. Two weeks is enough for a snapshot, and indefinite recording risks the same fixation that tracker data can cause. Keep one when something has changed or before an appointment.
It is not a replacement. Device data cannot record how rested you felt, how distressing a night was, or how your day went, and its sleep stage estimates are unreliable. Bring both if you like, with the diary as the main record.
It is a fair concern, which is why the once-a-day, time-limited format matters. One entry in the morning is different from checking a score repeatedly. If even that increases your anxiety, mention it to your doctor rather than pushing through.
This article sits in our section on sleep tracking and measurement. To understand what a device can and cannot see, read how accurate sleep trackers are and what your sleep score actually means. For the behavioural approaches a diary usually feeds into, see falling asleep and staying asleep. Our sourcing and correction standards are set out in the editorial policy.
Medical disclaimer
This article is for general information only. It is not medical advice, and it is not a substitute for diagnosis or treatment from a qualified healthcare professional. Do not start, stop, or change any medication, supplement, or treatment based on what you read here. If you have symptoms that concern you, contact a doctor. If your symptoms are severe or sudden, seek emergency care.
Every claim in this article links to its source in the text above. We use peer-reviewed research and high-authority health bodies, and we explain our sourcing standards in the editorial policy.
Medical disclaimer
This article is for general information only. It is not medical advice, and it is not a substitute for diagnosis or treatment from a qualified healthcare professional. Do not start, stop, or change any medication, supplement, or treatment based on what you read here. If you have symptoms that concern you, contact a doctor. If your symptoms are severe or sudden, seek emergency care.
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