(Pocket-lint) - Fitbit has announced its OS 4.1 software update that will bring a number of features to the company's smartwatches, comprising the Fitbit Versa 2, Fitbit Versa, Fitbit Versa Lite and the Fitbit Ionic

The OS 4.1 update will deliver the Smart Wake feature - a silent on-device alarm that users can set to wake them up with vibrations at a good time in their sleep cycle - to all Fitbit smartwatches, as well as Sleep Score on the smartwatches themselves rather than users having to open the Fitbit app.

There's also a new Agenda app for managing your schedule on the go and a new clock face switcher that allows users to store up to five clock faces and switch them to suit your mood or outfit.

For Versa 2 users, the OS 4.1 software update will see five additional Always-On display clock face options, expansion of Alexa's capabilities to being able to start any of the 20 exercises using your voice, as well as a battery saving feature that will disable some of the Verda 2's features to preserve battery life when you're running low.

The update - which is due to start rolling out to Fitbit smartwatch users from the first week of December - will also see a new PurePulse algorithm arrive on the Versa 2 smartwatch. The algorithm is said to use machine learning to recognise the unique signature of heart rate in the optical sensor in order to offer higher accuracy.

Fitbit has also announced its Fitbit Premium membership plan will see a new wellness report, more third party workouts, and more motivational tools like new guided programs and activity challenges appear over the coming months.

Writing by Britta O'Boyle.