Hi. I'm a software engineer at Fitbit. It is not my job to speak for Fitbit or to sell Fitbits, but I'm answering you because it gives me the chance to point out three reasons why this article's quote about Fitbits not being accurate about sleep stages is wrong.
1. The researcher is also an entrepreneur whose product's sales depend on people thinking Fitbit isn't good enough. https://sonicsleepcoach.com/about-dr-dan/
2. The quote lumps Fitbit and Apple Watch together in terms of how frequently heart rate is measured, when there's a 60x difference. A sincere quote would be more along the lines of "Apple Watch's 1-5 minute sample rate certainly isn't enough, but even Fitbit's 1-5 second sample rate won't give the accuracy you need..."
3. He doesn't say what's wrong with any published study showing sleep stage accuracy of Fitbit, notably https://academic.oup.com/sleep/article/40/suppl_1/A26/378095...
1. The researcher is also an entrepreneur whose product's sales depend on people thinking Fitbit isn't good enough. https://sonicsleepcoach.com/about-dr-dan/ 2. The quote lumps Fitbit and Apple Watch together in terms of how frequently heart rate is measured, when there's a 60x difference. A sincere quote would be more along the lines of "Apple Watch's 1-5 minute sample rate certainly isn't enough, but even Fitbit's 1-5 second sample rate won't give the accuracy you need..." 3. He doesn't say what's wrong with any published study showing sleep stage accuracy of Fitbit, notably https://academic.oup.com/sleep/article/40/suppl_1/A26/378095...