(Pocket-lint) - Apple is finally rumoured to be working on sleep tracking technology for its Apple Watch, according to a Bloomberg report. The company bought Beddit, a company that makes a sleep tracking sensor strip, in May 2017, so sleep tracking has long been a feature expected to come to the Apple smartwatch.

The report suggests people familiar with the matter have said Apple is testing the sleep monitor in several "secret sites" around its Cupertino headquarters, though it is not expected to come to the Apple Watch until 2020.

Sleep tracking is currently available to the Apple Watch through third party apps, but it's not a feature supported natively. It is however, a feature that is lacking from the device, especially with most of Apple's competition offering it. The latest Samsung Galaxy Watch Active offers four stages of sleep tracking for example, as do Fitbit's latest fitness trackers like the Charge 3

Those devices offer multiple days of use from a single charge however, certainly in the case of the Fitbit Charge 3 anyway. For sleep tracking to be a viable feature, a longer battery life will be a necessity for the Apple Watch, or at least fast charging support.

The Apple Watch Series 5 is expected to arrive around September 2019, though by the sounds of it, we won't be seeing sleep tracking until the Apple Watch Series 6. Hopefully that timeline will improve though. When it does arrive, we'd expect sleep tracking to play a part in Apple Rings too. 

For now, you can read our feature on everything else we would like to see on the next Apple Watch.

Writing by Britta O'Boyle.