Sleep diary or sleep tracker?

A sleep diary records the night as you experienced it; a tracker estimates it from sensors. For insomnia, the diary is what doctors ask for. A tracker can add detail, but it can't diagnose anything.

What a diary does that a tracker can't

Insomnia is partly about how sleep feels: lying awake, waking unrefreshed, being tired the next day. A diary captures that. The Consensus Sleep Diary paper notes the sleep diary has been regarded as the gold standard for subjective sleep assessment, and the American Academy of Sleep Medicine's insomnia guideline asks for a two-week sleep log before assessment.

A diary also records what a wrist can't see: the coffee at 16:00, the two glasses of wine, the stressful day, the medicine you started.

What trackers are and aren't

Consumer sleep trackers, such as watches, rings and bedside devices, estimate sleep from their sensors. The AASM's position statement says that without validation and FDA clearance they can't be used to diagnose or treat sleep disorders, and that their data should be seen as part of a full sleep evaluation, not instead of validated tools.

The AASM's insomnia guideline also notes that actigraphy, a research-grade wrist monitor, isn't routinely needed to assess insomnia, though it can help in some cases.

Using both

If you already wear a tracker, keep it. Fill in the diary from your own memory each morning first, then look at the tracker if you like. Where they disagree, write down how the night felt: that's what the diary is for.

If tracking numbers make you anxious about sleep, a diary alone is enough.

This guide isn't medical advice. If poor sleep has gone on for months or makes the day hard to cope with, see your doctor.