Nike has just updated the official Nike+ FuelBand iOS app to version 2.1.

Nike+ FuelBand 2.1 adds the ability to track when and how long you sleep using sleep on Nike+ Sessions.

It also adds support for session calibration, enabling you to calibrate your Cycling, Yoga and Training Sessions after your workout. In line with this, you will be prompted to edit your sessions to the most accurate NikeFuel score based on your intensity. NikeFuel, by the way, is Nike’s universal unit for measuring activities.

Nike+ FuelBand 2.1 also makes it easier to cheer your friends when they share sessions to a group.

If you can’t see the video embedded above, please click here.

Also including bug fixes and other improvements, Nike+ FuelBand 2.1 is available now in the App Store for free. It’s optimized for iPhone and iPod touch running iOS 6.1 or later.

Released in February 2012, Nike+ FuelBand was updated to version 2.0 early last month. Nike+ FuelBand 2.0 introduced a new design based on the look and feel of iOS 7. More importantly, it added support for a couple of features that require the new Nike+ FuelBand SE: Bluetooth 4.0 connectivity and the aforementioned Nike+ Sessions.

Coinciding with the release of Nike+ FuelBand 2.0, Nike launched the “motivational” fitness app Nike+ Move. Introduced at Apple’s iPhone 5s and iPhone 5c media event last September, Nike+ Move uses the iPhone 5s’ M7 motion coprocessor to convert movement into NikeFuel.