# Fit Bit Question **URL:** \ **Category:** Factual Questions\ **Created:** [January 7, 2018, 7:52pm UTC](https://boards.straightdope.com/t/fit-bit-question/806066 "2018-01-07T19:52:20Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![SanDiegoTim](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@SanDiegoTim](https://boards.straightdope.com/u/SanDiegoTim)\ **Post date:** [January 7, 2018, 7:52pm UTC](https://boards.straightdope.com/t/fit-bit-question/806066/1 "2018-01-07T19:52:20Z")
My wife just bought one. This morning she tells me her Fit Bit told her she went to sleep at a specific time. It also told her she was awake for a certain period of time. I assume this may have something to do with analyzing heart rate. Am I wrong and how accurate could this be? ---
**Author:** ![bb49](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@bb49](https://boards.straightdope.com/u/bb49)\ **Post date:** [January 8, 2018, 12:39am UTC](https://boards.straightdope.com/t/fit-bit-question/806066/2 "2018-01-08T00:39:32Z")
I’m not positive if it is always heart beat related. I went back and checked my Fitbit for a couple of nights. Dec. 27 I woke up briefly at 12:10 a.m. Just prior to that it showed me restless for a couple minutes. My heart beat didn’t change much during that time. It stayed around 48 to 51. If I get up during the night my heart rate will jump from around 50 up to 60 and fitbit will show I was awake for 3 or 4 minutes. But I do believe it is heart beat related. If you are restless or awake, normally your heart rate will increase a bit. Btw, I have a minor heart condition called SVT. It causes the heart to beat very rapidly. One night I woke up with an attack of SVT. In the morning I checked the fitbit and my heart had hit 160 beats per minute. The fitbit has given me useful information for My doctor. ---
**Author:** ![dofe](https://avatars.discourse-cdn.com/v4/letter/d/7ba0ec/32.png) [@dofe](https://boards.straightdope.com/u/dofe)\ **Post date:** [January 8, 2018, 12:52am UTC](https://boards.straightdope.com/t/fit-bit-question/806066/3 "2018-01-08T00:52:20Z")
According to [FitBit](https://help.fitbit.com/articles/en_US/Help_article/2163/?l=en_US&c=Topics%3ASleep&fs=Search&pn=1#AutomaticDetection), it’s a combination of heart rate and movements tracked by the sensor: > [@](#): > > Fitbit estimates your sleep stages using a combination of your movement and heart-rate patterns. When you haven’t moved for about an hour, your tracker or watch assumes that you’re asleep. Additional data—such as the length of time your movements are indicative of sleep behavior (such as rolling over, etc.)—help confirm that you’re asleep. While you’re sleeping, your device tracks the beat-to-beat changes in your heart rate, known as heart rate variability (HRV), which fluctuate as you transition between light sleep, deep sleep, and REM sleep stages. When you sync your device in the morning, we use your movement and heart rate patterns to estimate your sleep cycles from the previous night. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [January 8, 2018, 3:34am UTC](https://boards.straightdope.com/t/fit-bit-question/806066/4 "2018-01-08T03:34:24Z")
I was hopeful that the Fitbit would record sleep correctely. I have noticed that it has recorded me sleeping when I was reading in bed. On nights that I am not sleeping I have gotten up and gone downstairs to read or watch TV my Fitbit that as sleeping time. ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [January 8, 2018, 4:14am UTC](https://boards.straightdope.com/t/fit-bit-question/806066/5 "2018-01-08T04:14:24Z")
My knock-off brand doesn’t have a heart rate monitor, and it tracks sleep. So long as you don’t go for a walk after 10, it’ll track you as sleeping. So long as you move every few hours or so, it’ll still think you’re sleeping. If it records nothing all night, it says you weren’t wearing it. ---
**Author:** ![What\_the](https://avatars.discourse-cdn.com/v4/letter/w/f4b2a3/32.png) [@What\_the](https://boards.straightdope.com/u/What_the)\ **Post date:** [January 8, 2018, 2:55pm UTC](https://boards.straightdope.com/t/fit-bit-question/806066/6 "2018-01-08T14:55:15Z")
> [@Snnipe\_70E](#): > > I was hopeful that the Fitbit would record sleep correctely. I have noticed that it has recorded me sleeping when I was reading in bed. On nights that I am not sleeping I have gotten up and gone downstairs to read or watch TV my Fitbit that as sleeping time. I got a Charge 2, my first Fitbit, last week and sleep monitoring is what I need the most. I always wake up after about 3 hours and often take half of an Ambien to get back to sleep. Until last night, it tracked two separate sleep cycles. Last night I must have gone back to sleep soon enough or moved around minimaly such that it combined all of my night into one sleep cycle. I did research the optical sensor for heart monitoring because the thing hurts my wrist. Some users believe that the sensor is the cause. I think that I found that the sensor must be on to track sleep. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [January 8, 2018, 5:17pm UTC](https://boards.straightdope.com/t/fit-bit-question/806066/7 "2018-01-08T17:17:23Z")
My Fitbit (Flex 2) doesn’t have heart rate capabilities at all and still gives me a pretty good estimate on how long I sleep. I think it’s based entirely on motion. It seems to know when I am awake in bed reading _before_ I get to sleep, but sometimes will count the ten minutes after my alarm goes off where I’m zombie-reading Facebook as still sleeping. It also can tell the difference between me sleeping and just taking off my Fitbit and sitting it on a table somewhere. ---
**Author:** ![What\_the](https://avatars.discourse-cdn.com/v4/letter/w/f4b2a3/32.png) [@What\_the](https://boards.straightdope.com/u/What_the)\ **Post date:** [January 10, 2018, 2:50pm UTC](https://boards.straightdope.com/t/fit-bit-question/806066/8 "2018-01-10T14:50:05Z")
> [@DrCube](#): > > My Fitbit (Flex 2) doesn’t have heart rate capabilities at all and still gives me a pretty good estimate on how long I sleep. I think it’s based entirely on motion. It seems to know when I am awake in bed reading _before_ I get to sleep, but sometimes will count the ten minutes after my alarm goes off where I’m zombie-reading Facebook as still sleeping. It also can tell the difference between me sleeping and just taking off my Fitbit and sitting it on a table somewhere. FWIW…the Charge2 with the heart monitoring also tracks the stages of sleep… light, deep, REM and awake. I have no idea how well though.