Garmin International Inc announced the vívosmart 4, an activity tracker that introduces a wrist-based pulse ox2 sensor. According to the company, the new sensor allows customers to gauge their blood oxygen saturation levels at night to better understand their sleep quality.

“Sleep quality plays a critical role in your overall physical health,” says Dan Bartel, Garmin vice president of global consumer sales, in a release. “Poor sleep quality may contribute to the development of significant chronic conditions. With its slim design, the vívosmart 4 is comfortable to wear at night and pulse ox provides customers with information they can use to improve their health.”

In addition to pulse ox, the vívosmart 4 features Garmin’s new “advanced sleep monitoring,” which estimates light, deep and REM stages of sleep, along with movement throughout the night. Upon awakening, users can review their sleep stats in the Garmin Connect Mobile app.

The “Body Battery” energy monitoring feature can help with scheduling workouts, rest times, and sleep. Using a combination of data gathered from stress, heart rate variability (HRV), sleep ,and activity, a higher Body Battery indicates the time is optimal to be active whereas a lower number suggests rest is in order, according to the company.

The vívosmart 4 has a suggested retail price of $129.99.