Any ‘arm in a wrist device?

SLEEP trackers work by measuring your movement during the night.

The idea is that restlessness above a certain level indicates that you are awake, while periods of stillness suggest you’re asleep.

Wrist devices cannot accurately differentiate between light and deep sleep or identify periods of REM sleep.

REM sleep is the time in which your brain is at its most active, promoting learning and creating dreams.

So, despite the claims of various companies, new devices have little, if any, scientific validation.

The data certainly should not be used as the basis of a decision about your alertness or ability to safely undertake a

500-mile drive.

Recent research has shown that sleep tracking devices are mostly used by perfectly healthy people.

So they run the risk of joining what are known as the “worried well” – people who are worrying so much about improving their sleep that they stop themselves getting any. It’s such a problem the condition has even been given a name, “orthosomnia”.

There have even been reports of people telling GPs they have insomnia on the basis of data from their tracker.

My advice would be to simply ask yourself how you feel during the day.

If you feel awake, alert and focused, then you had enough sleep last night.