Sleep trackers more likely to ruin your slumber, says expert

Think getting a sleep tracker will help you catch more than 40 winks? You're dreaming, one expert says.

Smartphones and wearable gadgets like Fitbit have made it easy to track how much we move in our slumber.

"If you pay a billion dollars or whatever it is for one of these iPhone iWatches, you get all sorts of tinkly things in them," sleep physician Andrew Davies told The AM Show on Friday. "If you pay $50 for one, you just get a movement tracker.

"They usually link to a phone or your computer, and it extrapolates from the data how well you've slept."

But Dr Davies says they can't tell us much at all that's actually useful.

"They're very good for measuring movement, but they're not very good for measuring much else.

"You don't know whether someone's moving overnight because they're obstructing their airway, because of sleep apnoea or they're walking around the house. You can't tell - they're quite unreliable."

People who suffer from sleep apnoea regularly stop breathing while they're asleep. Sometimes, it's the result of a blockage in the airway, as a result of being overweight, sinus issues or a deviated septum.

For others, the brain simply doesn't instruct the body to make much effort.

Either way, a sleep tracker isn't going to help and may actually be harmful to people whose sleep issues are a consequence of their mental health.

"People who have an anxious disposition, people who are having problems with insomnia because of their anxiety, they wake up, they look at their watch - it's a bad night's sleep, they get anxious because they've had a bad night's sleep and it compounds the anxiety."

Dr Davies says it's normal to wake up a few times a night and teaching yourself not to worry about it will help more than any 'iDdevice'.

"People who put pressure on themselves to sleep go to bed anxious… that's going to impair your sleep. You lie there catastrophising."

Sleep experts from around the world are meeting this week in Auckland at SkyCity for the Sleep DownUnder conference.