Garmin Index Sleep Tracker L/XL Black

The Garmin Index Sleep Monitor L/XL is an arm-worn sleep tracker designed for overnight recovery analysis. It works as a standalone optical sensor rather than a chest-strap heart-rate monitor. The internal lithium-ion battery provides up to 56 hours of continuous use between charges. Data synchronisation occurs through Bluetooth 5.0 with Bluetooth Low Energy. The monitor transmits its recordings directly to the Garmin Connect app on iOS and Android smartphones.

The sensor weighs 14.5 grams and features a plastic housing paired with an adjustable strap made of 70% nylon and 30% spandex. The breathable band fits upper arm circumferences from 26 to 42 centimetres. Durability extends to a 50-metre water-resistance rating, allowing use in the shower or pool. The system also integrates with compatible Garmin smartwatches to consolidate health metrics. A USB charging and data cable is included for powering the unit.

• Tracks overnight heart-rate variability and blood oxygen saturation
• Generates a sleep score alongside stress and Body Battery metrics
• Housing dimensions measure 41.7 mm wide by 37.6 mm deep by 7.8 mm high
• Black exterior colour offers a neutral aesthetic for nighttime wear
• Maximum strap length extends to 420 mm to accommodate larger arms
• Dedicated sleep-tracking form factor rather than a continuous wrist watch