The Owlet Smart Sock is a wearable baby monitor that wraps around your infant’s foot and tracks heart rate and blood oxygen levels while they sleep. It uses the same type of sensor technology found in hospital pulse oximeters, miniaturized into a soft fabric sock that connects wirelessly to a base station and smartphone app. The current version, called the Dream Sock, is the first over-the-counter infant monitor to receive FDA clearance as a medical device, granted on November 8, 2023.
How the Sock Works
The sensor inside the sock uses pulse oximetry, the same light-based technology hospitals use when they clip a sensor to your finger. It shines light through your baby’s skin and measures how much is absorbed by the blood, which reveals two things: how fast the heart is beating (pulse rate) and what percentage of the blood is carrying oxygen (oxygen saturation). The sock sends this data wirelessly to a base station that sits nearby, and from there to the Owlet Dream App on your phone.
Each Dream Sock comes with four fabric socks in two sizes, with left and right versions, designed to fit babies from 1 to 18 months old weighing between 6 and 30 pounds. The sensor unit snaps into the fabric sock and sits against the top of the foot.
What the Notifications Mean
The base station uses colored lights and sounds to alert you when something needs attention. A red light with a loud alarm is the most urgent: it triggers when the measured pulse rate drops below 50 bpm or rises above 220 bpm, or when oxygen saturation falls below 80%. These are extreme values that fall well outside normal ranges for a healthy infant.
A yellow light with a softer alarm means there’s a technical issue rather than a health concern. This typically means the sock has shifted position, fallen off the baby’s foot, or lost its wireless connection to the base station for more than 60 seconds. You also receive push notifications through the app for both alert types, so you don’t have to be in the same room as the base station.
How Accurate It Is
The FDA clearance process required Owlet to submit clinical data proving the sock’s accuracy. In a home study of 35 infants (between roughly 1 and 18 months old), the oxygen readings were accurate within about 2.16%, and pulse rate readings were accurate within about 3.5 beats per minute, both compared against medical-grade reference monitors. For context, the FDA’s acceptance threshold is less than 3% error for oxygen and less than 5 bpm for pulse rate, so the Dream Sock passed both benchmarks.
In a separate study conducted in a neonatal intensive care unit, 66 patients were monitored simultaneously with the Dream Sock and hospital-grade equipment. The sock correctly identified 100% of true low-heart-rate events and had a 99.86% accuracy rate for oxygen desaturation alarms, meaning it produced almost no false negatives for dangerous drops.
The Product’s Regulatory History
The path to FDA clearance was not straightforward. The earlier version, called the Smart Sock 3, displayed live pulse rate and oxygen readings and sent red alerts when values fell outside preset ranges. In late 2021, the FDA told Owlet that these features made the Smart Sock 3 a medical device, which meant it couldn’t be sold without going through the formal clearance process. Owlet pulled the health notification features from the market.
The company then released a scaled-back version called the Dream Sock, which functioned as a “wellness device.” It showed a 10-minute average of oxygen saturation rather than live readings, and it delivered sleep-related prompts based on changes from a baby’s personal baseline rather than medical-style alerts. After completing the FDA’s De Novo review process, Owlet received Class II medical device clearance in November 2023 and restored live oxygen and pulse rate readings along with the health notifications.
Sleep Tracking Features
Beyond health monitoring, the Dream Sock tracks your baby’s sleep patterns through the companion app. It logs total sleep time, the number of wakings, and whether your baby is in light or deep sleep at any given moment. After about ten minutes of monitoring, the app begins building a visual timeline of the sleep session showing how your baby cycled between sleep stages.
The app also includes a predictive sleep feature that uses your baby’s age and accumulated sleep data to suggest nap times and bedtimes. If you pair the sock with the Owlet Cam 2, the app combines the sock’s biometric data with environmental readings like room temperature, humidity, and noise level, giving you a more complete picture of what’s affecting your baby’s sleep.
What Pediatricians Say
The American Academy of Pediatrics does not recommend home infant monitors as a strategy to reduce the risk of sudden infant death syndrome (SIDS). The AAP’s concern is twofold: there isn’t enough data to show these devices actually prevent SIDS, and there’s a risk that parents who use them may feel a false sense of security and become less diligent about proven safe sleep practices like placing babies on their backs and avoiding bed-sharing. The FDA clearance confirms the device accurately measures what it claims to measure, but that’s a different question from whether routine monitoring of healthy infants improves outcomes.
The Dream Sock is cleared for use on healthy infants in the home. It is not intended to diagnose or treat any medical condition, and it is not a substitute for a medically prescribed monitor for infants with known health concerns.