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Understanding How the Owlet Smart Sock Works

November 5, 2018

If you’ve ever been to the hospital, you might remember a little clip about the size of a clothespin gripping your finger. That clip is called a pulse oximeter, and it shines a little light through your skin to measure how much light is absorbed by your red blood cells, which varies depending on how much oxygen is bound to them. Simply put, that little clip helped keep track of important information while you were resting up in your hospital bed.

What’s the Difference?

Traditional baby monitors transmit sound from one room to the other, or step up the game to transmit video from your baby’s nursery to your room. Here at Owlet, we wanted a baby monitor that did a little more. Being parents ourselves, we trust our eyes and ears, of course, but sometimes sights and sounds don’t communicate everything that could be going on with babies.

Enter the Owlet Smart Sock.

We worked, and built, and tested – just to re-work, re-build, and re-test to make a baby monitor that uses the amazing hospital technology many of us were familiar with. Pulse oximetry tailored to work in a baby monitor offers a better picture of what is going on with our babies. Is there anything cooler than being able to open up an app and see what’s going on in the news, or the weather, or with your beloved Golden State Warriors? We don’t think so: technology has brought all of our favorite things to our fingertips. It really makes sense to use technology to make one of the hardest jobs in the world a little easier, doesn’t it?

Owlet Monitor and Sock

What does the Owlet Smart Sock do, exactly?

Check on your little one without disturbing their sleep. Using pulse oximetry, the Owlet Smart Sock tracks your baby’s heart rate and oxygen levels and sends real-time insights to your phone. The Smart Sock is designed to grow with your baby which is why it comes with three different fabric sock sizes that comfortably wrap around your baby’s foot. 

It also includes a Base Station which glows green to reassure you baby is okay but will notify you if heart rate and oxygen levels leave preset zones. The Base Station was designed with different notifications, including notifications for heart rate and oxygen falling outside of range (red), Bluetooth disconnect between the Smart Sock and Base Station (blue) and inability to get a proper reading (yellow). Learn more about these different notifications on our website. *Always remember to contact your pediatrician for any specific questions you have regarding your baby.

Baby Monitor

Bringing Parents Peace of Mind and Sleep

Knowing what your baby needs and when they need it is a cause for stress and anxiety with most new parents. As one of the pioneers for in-home monitoring of infants, we felt a big responsibility to provide superior technology and peace of mind for parents. A recent study in Global Pediatric Health showed that not only do 96% of parents using the Owlet Smart Sock feel less anxious but 94% of parents report better sleep quality.

Our mission at Owlet is to provide better care access for babies in the home by empowering parents with the right information at the right time. The Owlet Smart Sock gives parents peace of mind and allows you to check in on your little one while they’re sleeping so you too can get some rest. Because when you get the sleep you need, your baby gets the mom and dad they deserve and that’s priceless.

*Owlet is intended to provide peace of mind.  It is not intended to diagnose, treat, mitigate, cure, or prevent any disease or condition. This is not a medical device and is not intended for use as a medical device or to replace a medical device. The Owlet Baby Monitor is only intended to assist you in tracking your baby’s wellbeing and is not intended to replace you as a caregiver. You are ultimately responsible for your baby. This device is not intended to cure, treat, or prevent any disease or health condition, including, but not limited to, Sudden Infant Death Syndrome (SIDS).

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The Smart Sock is the first baby monitor to track your baby’s oxygen level and heart rate—good indicators of Baby's overall well-being—while they sleep. If your baby’s readings leave preset zones, you'll receive a notification that lets you know your baby really needs you. Now you can feel more confidence, more freedom, and more peace of mind knowing that Owlet is here to help.

Our all-new Smart Sock is the third of its kind and it's smarter than ever.

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20 thoughts on “Understanding How the Owlet Smart Sock Works


Hi Peggy! Movement will affect how sleep is tracked as it’s part of the algorithm we created to determine sleep/awake times.



How accurate is it’s measurement of sleep? My baby tosses and turns a lot in his sleep but is still sleeping. The Owlet seems to measure that he’s awake but my video monitor shows he’s asleep and just tossing and turning?


Hi there! We reached out to our team and this is what they said-

“Safety is a top priority at Owlet. In fact, one of our primary missions is to keep babies safe.

Consequently, we adhere to all industry and governmental standards, including the voluntary consensus standards of the American National Standards Institute and the global standards of the Institute of Electrical and Electronics Engineers or ANSI/IEEE. The ANSI/IEEE does not recognize electromagnetic frequencies or EMF as a standard of testing because EMF only comprises one segment of overall product energy.

Instead, ANSI/IEEE standards are based upon the Specific Absorption Rate or SAR measurement in determining product safety. SAR is a value that corresponds to the relative amount of radio frequency energy absorbed. The safety limit for SAR exposure is 4 watts/kg. Independent testing of the Owlet Smart Sock 2 is .0008 watts/kg, which is 5,000 times below the safety limit.”



What level of radiation is released from the sock? Is it harmful to the baby?


Hi Bettina! The thresholds are as follows- heart rate: 60-220 bpm and oxygen: 80-100%.



What is the preset range that the alarm goes off when it gets below?


Hi Jackie, the Smart Sock is a consumer device and not a medical device. It is only intended for use with children up to 18 months or 25 lbs and should not be used on any other body part besides on the foot.



What is accuracy of Owlet on older children over 18 months? Can owlet be utilized on hand or finger on older children as used in hospital setting.


Hi Adriana, these thresholds are in place for a few reasons, one being that a baby can quickly desat and come right back up. This helps avoid false notifications due to fluctuations.



Why is it set at such low value ?


Hi Ashley, we use different algorithms that use motion and heart rate and oxygen level to determine the differences.


Ashley Downes

I have the owlet connected app and it also monitors his sleep patterns how accurate is that. How does it determine weather he’s truly sleeping or truly awake.


Hi Margaret, the Smart Sock continuously takes readings and sends them to the base station every few seconds.


Margaret Gibbons

First of all, love the Owlet sock! I was just wondering how often the Owlet sock actually checks the readings of my baby? I’ve only had one red alarm and that was when I was feeding her and forgot to turn it off… and two yellow alarms when the sock shifted. Is there a certain time the sock actually checks like every few minutes or is it constantly monitoring?


Hi Christie, you’ll receive a notification once oxygen drops below 80%.



At what Oxygen Satuartion % does the alarm set off at?



Hi Sam, we understand your concern. You are correct in that pulse oximetry does not measure carbon dioxide levels and neither does the Owlet. If you are concerned about your daughter, we suggest reaching out to your physician to discuss this.



We have been using the owlet and very happy with the device. My daughter recently began rolling over and sleeping on her stomach. Sometimes I find her face down and I will reposition her. I am very worried about her breathing in recycled air. Since pulse oximetry cannot measure carbon dioxide levels, is my baby at risk even if her oxygen levels are normal? Can you please clarify if a normal oxygen reading means that carbon dioxide is normal as well?



Hi Adrienne! You are correct, pulse oximetry does not detect carbon monoxide. We would suggest having a carbon monoxide detector in your home. We will be sure to pass your concern along to our engineering team!



What about the fact that pulse oximeters can not differentiate between oxygen and carbon monoxide saturation in the blood? I just purchased an Owlet, waiting for it to be delivered, but learning that it can NOT detect carbon monoxide poisoning has taken away a sense of peace for me. What do you have to say for this?