Sleep diary vs. sleep tracker: a sleep app that needs no wearable

Sleep apps fall into two broad types: trackers that measure your sleep with a wearable or your phone's sensors, and diaries that you fill in yourself each morning. If you can't sleep, the right choice depends on what you want to learn.

How they differ

	Sleep tracker	Sleep diary
How it works	A watch, ring, or phone on the bed estimates sleep from movement, heart rate, or sound	You log bedtime, time to fall asleep, night awakenings, and wake time each morning
Device	Wearable, or phone near the pillow	Just your phone, used in the morning
What it captures	Estimated sleep stages and movement	Your own experience of the night
Used in CBT-I	Not the standard tool	The standard tool (Consensus Sleep Diary)

Can a tracker make things worse?

Sleep researchers have described "orthosomnia": some people become preoccupied with getting perfect tracker scores, and the worry itself makes sleep harder. Consumer trackers also estimate sleep stages less precisely than a sleep lab. If checking a score at night makes you anxious, a diary may suit you better.

Who each one suits

• A tracker suits people who are curious about their sleep and comfortable wearing a device.
• A diary suits people who can't fall asleep or keep waking at night and want to see their pattern the way CBT-I does, without a device or recording.

Nyxtune is a diary-type app

Nyxtune is an iPhone sleep diary. It needs no wearable, does not record sound, and you don't keep your phone in bed. You log last night each morning — rough estimates are fine — and review charts of your sleep time and time to fall asleep. The dark screen is easy on the eyes if you open it at night.