I replaced my smartwatch with Garmin's new sleep tracker for weeks - here's my verdict

Garmin Index Sleep Monitor

ZDNET's key takeaways

• The Garmin Index Sleep Monitor is available for $170 in S/M and L/XL sizes.
• The band is very comfortable and lightweight, the monitor tracks up to seven nights of sleep, and the sleep/recovery metrics are well integrated into the Garmin Connect ecosystem.
• It's still fairly expensive for a single-purpose wearable, even though FSA/HSA coverage is supported.

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As a regular reader of my work, you likely know I'm a fan of Garmin watches, especially for the built-in LED flashlight I use daily.

I've been hoping for a smart ring that could sync with Garmin Connect, allowing me to gather key metrics for recovery and training status without wearing a bulky watch to bed. While a smart ring isn't yet an option, Garmin has introduced a single-purpose wearable to fill the void: the Index Sleep Monitor.

Also: The best Garmin watches you can buy: Expert tested

The Index Sleep Monitor is designed to track a week of sleep and integrate that data into your Garmin Connect ecosystem and smartwatch. While you can use the monitor without a Garmin watch, you'll be limited to viewing sleep details in the smartphone app.

The system consists of an ultra-comfortable band that measures 2.5 inches wide. Two varying lengths are available, depending on your upper arm circumference. The L/XL size fits my arm the best, but there is also an S/M size available. 

Also: The best smart rings of 2025: I tested and found an obvious winner

The band weighs only 16 to 20 grams, depending on the size, and I cannot stress enough how extremely comfortable it is to wear every night. That aspect of the product may be its most important, considering it would replace something just as subtle as a smart ring.

Matthew Miller/ZDNET

The Index Sleep Monitor module is also light at 14.5 grams (0.5 ounce) and charges up with a standard Garmin charging cable. Garmin advertises up to seven nights of sleep tracking with eight hours of sleep. I generally sleep about 7.5 hours per night, and the advertised battery life has been accurate.

I keep the Index Sleep Monitor on my nightstand and slide it on when I go to bed. I test a lot of wearables, but my preference is not to wear a watch when I sleep since I roll, and watches sometimes get hung up underneath me, causing me to lose sleep data. 

The Venu X1 has been great to wear to sleep with its ultra-thin form factor, but my sleep has been even better when I am only wearing the Garmin Index Sleep Monitor.

Matthew Miller/ZDNET

Beyond its sleep tracking capabilities, the Index Sleep Monitor features an alarm with a "Smart Alarm" function -- a capability also found on the Venu X1 and Vivoactive 6. This feature can wake you gently during a light sleep phase up to 30 minutes before your scheduled time.

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The alarm itself is a vibration with three adjustable intensity levels. A double tap on the monitor will snooze the alarm for 10 minutes, while four taps will stop it entirely.

Matthew Miller/ZDNET

The Index Sleep Monitor captures a comprehensive set of metrics, including total sleep, stages, movement, breathing disturbances, resting heart rate, heart rate variability, blood oxygen, and skin temperature. This data is critical, as it feeds directly into Garmin's Body Battery, recovery, and women's health calculations.

Also: Why I swear by this Garmin smartwatch over competing models (including the Apple Watch Ultra)

While the monitor offers a way to collect these insights without wearing a watch to bed, its $150 price point is difficult to justify given that many Garmin watches provide similar functionality. A price closer to $99 would make its value proposition more compelling.

Battery life is accurate and the light monitor charges quickly

At its current price, the Index Sleep Monitor could serve as more than just a sleep tracker. Its sleek design and band are well-suited to function as a heart rate monitor for activities where a watch isn't allowed or optimal, such as basketball or football, capturing vital performance data.

Also: I've tested the Apple Watch, Oura Ring, and other sleep trackers - 5 tips to get the best results

After several weeks of use, the monitor has consistently provided more accurate sleep data than a watch, which sometimes showed gaps. This newfound accuracy, along with the comfort of not wearing a watch to bed, allows me to fully commit to the Garmin ecosystem, no longer needing to supplement with a smart ring for key metrics.

ZDNET's buying advice

Wearing a watch to track sleep can lead to frustrating data gaps, undesirable battery drain, and discomfort. The Garmin Index Sleep Monitor offers a more comfortable and accurate system for capturing key health metrics. The device feeds this data into the Garmin ecosystem, providing a holistic, full-body status report that has greatly improved my outlook. 

I just wish the device were more accessibly priced, as its $170 sticker tag can make it difficult to justify for some consumers, especially for being a single-purpose gadget.