Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s), and is presented for informational purposes only. We recommend that patients follow their doctor’s guidance in regard to medical devices.
The Fitbit Sense is one of the brand’s most popular devices. Fitbit claims this product can help users “manage stress” and “put heart health first.”
In this article we’ll review the features of the Fitbit Sense based on published medical research to determine if there’s evidence backing its proposed health benefits, or if it’s a waste of money.
Can Fitbit Sense Manage Stress?
Fitbit claims this product can help users manage and reduce their stress levels through an electrodermal (EDA) activity sensor. This sensor detects for increased sweating as a stress signal, as explained in their informational video below:
EDA is shown in early medical research to be a method of tracking changes in stress levels, but we don’t find these insights particularly useful.
When a user is stressed, Fitbit Sense suggests meditation, but meditation can be practiced with or without Fitbit. And most people know when they’re stressed and don’t need a device to tell them so.
We find it somewhat deceiving for Fitbit to claim they help users “manage” stress. What their device is really doing is tracking stress levels, and then suggesting that users manage their own stress. Most stressed people know that actively managing stress through meditation would benefit them; it's the implementation and motivation that’s often a challenge.
The EDA sensor doesn’t even appear to passively track stress throughout the day, which would be somewhat valuable because it could alert people that they’re stressed when they weren’t conscious of it. Instead, it has to be used actively. So a user needs to select the EDA app and place their palm on the screen to get a stress reading.
This seems to us like a solution in search of a problem, and biometric technology that may be cool and innovative, but not particularly useful.
Meditation is free and is a research-backed tool to reduce stress levels, and we outlined an effective methodology in our medical meditation review article. Just meditate without an app telling you to and save the money.
Can Fitbit Sense Help Heart Health?
As stated in the intro section, the core secondary health claim that Fitbit makes about the Sense is that the device can help heart health. The Sense has electrocardiogram (ECG) technology that can track the heartbeat and notify users of early signs of a condition called atrial fibrillation (afib).
It’s extremely important to note that, just like the stress detection functionality, the ECG does not work passively in the background, and only works when users proactively open an ECG app and place their fingers on the device for 30 seconds.
This is important because, beyond being an annoyance, one of the main theoretical benefits of biometric devices is that they run 24/7 and provide early alerts about symptoms that users wouldn’t have thought to check, which can be valuable for further medical testing.
If a user needs to proactively open the ECG app every day to test for afib, compliance will be lower. It will also be significantly inferior to a solution that provides constant passive tracking, which would result in a greater pool of data and more accurate results.
A medical trial published in the Journal of Sports Sciences in 2019 compared heart rate measures from various commercial tracking devices, including the Fitbit. The researchers found that the Apple Watch was significantly more accurate than the Fitbit.
Relative error rates (RER) from the Apple Watch ranged from 2.4% to 5.1%, while RER from the Fitbit ranged from 3.9% to 13.5%. This test used the Fitbit Charge HR 2 device rather than the Sense, but still seems relevant.
A more recent medical review assessed wrist-worn heart rate monitors for atrial fibrillation and concluded that “further improvements in device technology are needed before integrating them into the clinical management of rate control in atrial fibrillation.” The researchers demonstrated that the devices, including the Fitbit Charge HR, were not accurate enough to provide reliable medical data.
Fitbit claims in the heart health section of their website that the Sense is “validated in a clinical study to provide accurate results,” but they do not link to that study in any readily-apparent way where they make this claim on their site, and we cannot locate a medical study validating the accuracy of Fitbit Sense.
From the available research, we will disagree with Fitbit’s claim that their device helps “put heart health first.” It seems to us to be a waste of money at this stage. Patients who believe they’re suffering from atrial fibrillation should speak to their doctor, because medical ECG testing using standard devices is likely to be much more accurate than using a Fitbit.
Fitbit Sense Vs. Versa 3
The Fitbit Versa 3 is the slightly older version of the device, and is also more expensive than the Fitbit Sense at the time of writing ($229.95 for the Versa 3 and $199.95 for the Sense).
Only the Fitbit Sense has the EDA stress monitor and the ECG heart rate monitor, so it seems technically superior in our opinion.
We can’t identify any clear benefits of the Versa 3 over the Sense, so for consumers set on purchasing a Fitbit we’d recommend the Sense, especially when it’s on sale at a lower price as it is currently.
Fitbit Sense Vs. Apple Watch 6
The Apple Watch technology appears to be superior to Fitbit technology in terms of heart rate monitoring, as evidenced by the previously-linked medical study. We believe the Apple Watch 6 is the better choice for consumers looking specifically for heart rate monitoring and afib risk.
The Apple Watch 6 also passively tracks blood oxygen levels. While this is an interesting novelty and may appeal to some users on a purely technical level, there doesn’t appear to be much medical evidence for the benefit of blood oxygen tracking for the everyday consumer.
Low blood oxygen levels can require medical intervention (like in the case of severe COVID-19 infection), but patients would have symptoms well before that stage that would prompt them to seek emergency medical attention. It doesn’t appear to be a metric worth passively monitoring.
Both the Apple Watch 6 and the Fitbit Sense track sleep data. This can be valuable to users, because understanding sleep quality can help you optimize it (or seek medical attention such as a sleep study that can detect conditions impacting sleep).
An extremely thorough medical review of wearable technology for tracking sleep analyzed data from 9 different devices and found that the Fitbit was the most accurate for tracking Total Wake Time (TWT) and the third-most accurate for tracking Total Sleep Time (TST).
A wearable ring called Oura which we recently analyzed in our Oura Ring reviews article was the most accurate for tracking TST.
There is no medical data directly comparing the sleep-tracking capabilities of the Fitbit Sense against the Apple Watch 6, but we would recommend the Fitbit device to sleep-conscious consumers because it appears to have relatively accurate data.
Fitbit Sense Pros and Cons
Below are some quick takeaways for readers that may not be interested in all of the research behind our conclusions:
Pros:
- Can provide useful ECG data
- Often on sale cheaper than older Fitbit model
- Stress detection likely accurate
Cons:
- Data generated not especially useful
- Data generated not especially accurate
- Requires monthly subscription for full functionality
Fitbit Sense FAQ
Is Fitbit Sense Waterproof?
Fitbit claims the device is water-resistant up to 50 meters in one of their help articles. The band may be damaged in water if it’s made from leather, metal or woven materials.
Users planning on swimming with their Fitbit should likely purchase a silicone band, which they brand as Sport Bands, as these are unlikely to be damaged by water.
What Was Fitbit Sense’s Release Date?
According to Wikipedia, the Fitbit Sense was launched in September of 2020 and is the brand’s newest model at the time of writing.
When Will Fitbit Sense 2 Release?
There is no scheduled date of release for Fitbit Sense 2 at the time of writing this article, but rumors from major tech publications speculate the release will be later in 2022.
Fitbit doesn’t tend to announce specific release dates far in advance.
Does Fitbit Sense Track Blood Pressure?
Fitbit Sense doesn’t currently track blood pressure, but the company announced in April of 2021 that they’re piloting studies on a novel way to passively track blood pressure without the need for the traditional arm cuff.
If they succeed, this would be a revolutionary breakthrough because significant blood pressure fluctuations throughout the day can make once-annual annual checks relatively inaccurate.
