A sleep diary is a few lines each morning about when you went to bed, when you got up, how you slept and what might have got in the way. The NHS suggests one when it's looking for what sets off sleepwalking or night terrors, and the same notes work for any bad night. It's the low-tech version of a sleep tracker, and the more honest one.
Sleep diary in brief
Each morning, note your bedtime and getting-up time, roughly how long it took to fall asleep and how well you slept. Include any caffeine or alcohol, whether you felt tired or stressed, and how you felt the next day. A week or two gives you several nights to compare. Look for patterns and change one thing at a time, and take your diary to your GP if things don't improve.
Write down a few things each morning
The NHS sleepwalking advice suggests recording what time you went to bed, how well you slept, whether you had caffeine or alcohol and whether you felt tired or stressed.1 Its night terrors advice adds how long you slept, how long it took to fall asleep and how you felt the next day.2
Fill it in each morning, before the day blurs the night.
This diary keeps a week of nights in your browser only, and prints out for a GP appointment.
Your sleep diary for one week
Each morning, note when you went to bed, how long it took to fall asleep, when you got up, how you felt the next day and anything like caffeine, alcohol or stress.
Look for patterns, then change one thing at a time
After a week or two, compare bad nights with good ones for late caffeine or alcohol, late screens, stressful days and wandering bedtimes. That's exactly how the NHS uses a diary when it's hunting for the trigger behind sleepwalking or night terrors. Change one thing at a time, or you won't know what worked. Try our guide to junk sleep for more on poor sleep, and use our sleep calculator to pick a regular bedtime.
Your diary shows your three worst nights all followed a glass of wine after 9pm. What's the best next step?
- Buy a sleep tracker to measure it properly
- Skip the late drink for a week and keep writing
- Change your bedtime, your diet and your pillow all at once
Change one thing and keep the diary going, so you can see whether that one change made the difference.
A diary records how you feel, which a tracker can't
Sleep trackers are mostly a gimmick, to my mind: the sleep stage data is a guess, and a bad score can make a perfectly fine night feel bad. I'd rather you noticed whether you felt rested than let a number decide for you. A diary gives you somewhere to put that feeling into your own words, before you start doubting it.
If you already wear one, the bedtime and wake times are handy to copy into your diary, but the "how did I feel" column is yours.
Take your diary to the GP
The NHS says a GP will try to find out what's causing your insomnia, and a diary gives them something to go on.3
Bring the notebook to the appointment, and let the GP look for the cause with you.
See a GP if:
- changing your sleeping habits has not helped your insomnia
- you've had trouble sleeping for months
- your insomnia is affecting your daily life in a way that makes it hard for you to cope
Sleep researchers and clinicians use diaries too. Carney and colleagues brought together sleep experts to agree a standard sleep diary, tested with good sleepers, people with insomnia and people with sleep apnoea, and written to be easy to fill in.4 The paper is about the format of a diary, not proof that keeping one improves sleep.
You don't need to work out the cause on your own, because that's what the GP is for. The NHS says months, but honestly, a month of this and I'd be booking the appointment. If you're struggling tonight, our guide to what to do when you can't sleep has practical advice for getting through a wakeful night.
Questions people ask about sleep diaries
How long should I keep a sleep diary?
A week or two is a sensible start. That gives you room to include work days and days off, rather than judging your sleep by one part of your routine. Keep going while you're testing a change so you have something to compare. If the problem has lasted months, take what you've recorded to your GP rather than waiting to finish.
What should I write in a sleep diary?
Note your sleep times, how you slept and how you felt, alongside anything that might have affected the night. The NHS suggests bedtime, sleep duration, time taken to fall asleep, sleep quality, caffeine or alcohol, tiredness or stress, and how you felt the next day. Add your getting-up time too. Keep each entry short enough that filling it in doesn't become a chore.
Is a sleep tracker better than a sleep diary?
No, not for working out what might be wrong with your sleep. A wristband can tell you when you lay down, but its guess at your sleep stages is just that, and it has no idea how you felt. Your own notes record what you did and how you felt afterwards. Use the tracker's bedtime and wake times if you find that convenient.
