REM, Light, Deep: How Much of Each Stage of Sleep Are You Getting?

sleep stages: man tracking his sleep using Fitbit Alta HR

Waking up tired, angry, or cranky? If you use a Fitbit Alta HR, Fitbit Charge 2, or Fitbit Blaze, your sleep data may soon be able to reveal why. By tapping into your nighttime heart rate and movement patterns, these devices will be able to estimate how much time you spend in light, deep, and rapid eye movement (REM) sleep. Pretty cool, right? Each of these stages—or sleep types—serve a different purpose, so understanding how much of each stage you log can help you identify and address sleep-related issues. Below, a breakdown of what you need to know about each sleep stage.

Sleep Stages, Simplified

Sleep researchers divide sleep into five stages—stages 1, 2, 3, 4, and REM—but to keep things simple, Fitbit groups like sleep stages together. In the app, your sleep will fall into three stages: light, deep, and REM. Here’s what each of those mean.

fitbit sleep stages hypnographLIGHT SLEEP

Stage 1: “This is the sleep that’s a little more choppy, shallow, not restful,” says Michael Grandner, MD, director of the Sleep and Health Research Program at the University of Arizona in Tucson and a Fitbit sleep consultant. “But it’s usually just a quick transition, so you’re not in it for very long.

During stage one, “you’re still hearing things and have a sense of awareness,” says Fitbit sleep consultant Allison Siebern, PhD, consulting assistant professor at The Stanford Center for Sleep Sciences and Medicine and director of Sleep Health Integrative Program at the Veterans Affairs Medical Center in Fayetteville, NC. “Your brain has dipped into sleep but you don’t feel like you’re asleep.”

Stage 2: When people talk about light sleep, this is the stage they’re usually referring to. You’re asleep but can be easily awoken. That said, stage 2 sleep is not shallow, nor is it less important than other sleep stages. “Light sleep is very important because it takes up more than half of the night,” says Grandner. “It’s when your body processes memories and emotions and your metabolism regulates itself. So there’s a lot of body maintenance occurring during lighter stages of sleep.” Breathing and heart rate typically decrease slightly during this stage.


Stages 3 and 4: During deep sleep, you become less responsive to outside stimuli. Breathing slows and muscles relax; heart rate usually becomes more regular.

“Deep sleep is very much about the body,” says Grandner. “The thinking parts of the brain are largely offline. Your muscles are very relaxed. You’re not dreaming at all during this time. Your body is doing a lot of rebuilding and repairing.” Deep sleep is when your body secretes growth hormone, which is associated with cellular rebuilding and repair. According to Siebern, deep sleep has also been shown to help strengthen your immune system.


“If deep sleep is about body, REM is about the brain,” says Grandner. “The brain is very active during REM sleep, yet the body is very inactive. Actually it’s so inactive, you’re actively paralyzed during REM sleep.”

REM is when most dreaming happens and your eyes move rapidly in different directions (hence the name). Heart rate increases and your breathing becomes more irregular.

REM is very important for emotion regulation and memory—you’re clearing the brain of things that aren’t needed, says Siebern. It’s also the peak of protein synthesis at the cellular level, which keeps many processes in the body working properly.

Understanding Sleep Cycles

Your body doesn’t just hit each sleep stage once a night, nor does it spend an equal amount of time in each of them. In fact, it cycles through all of these stages multiple times a night. “Each cycle lasts, on average, 90 minutes,” says Grandner, “but some cycles can be as short as 50 minutes and some can be as long as 100 minutes or more.” Here, according to Grandner, is how it works:

Cycle 1: During light sleep you’ll dip into stage one and transition into stage two. Then you’ll move quickly into deep sleep, where you’ll stay for a while before going into 10 minutes or so of REM. “It’s very hard to wake up from deep sleep, which is why your body tries to get it over with as quickly as possible,” says Grandner. “By the time the night’s halfway over, you’re done with it.”

Cycle 2: You’ll get slightly more light sleep, still a lot of deep sleep (but less than before), and a little more REM.

Cycle 3: You’ll probably log a lot more light sleep, a little bit of deep sleep, and more REM.

After this, during the second half of the night, the cycles mostly break down as your body alternates between light sleep and REM for the rest of the night.

How Do Your Sleep Stages Stack Up?

When you click on the sleep tile from your Fitbit dashboard and then choose Today, you’ll be able to see how much time you spent in each sleep stage and what percent of your total night’s sleep that stage constituted.

Fitbit Sleep Stages Today

On average, light sleep will take up about 50 to 60 percent or more of your night. “Whether you get more or less light sleep isn’t really going to affect how you feel too much, because it’s just whatever time is left that’s not spent in deep sleep or REM,” says Grandner. “It’s sort of the remainder.”

Deep sleep, on the other hand is likely to take up 10 to 25 percent (depending on your age) of your sleep. “There’s no real way to get too much deep sleep,” says Grandner. “Your body has its own natural drive for it, so once you meet that, the need will dissipate and you’ll just start going into REM and light sleep.”

Too little, on the other hand, and sleep becomes unrefreshing. “The two main things that can lead to less deep sleep is age—people naturally get less as they get older—and anything that interferes with your sleep, like pain, illness, medical problems, sleep apnea, and other sleep disorders,” says Grandner. “They can keep you out of deep sleep artificially, which makes your sleep a little more shallow.” Also, shift work. “Your body wants to get into deep sleep at night, and it wants to avoid deep sleep during the day,” says Grandner. “ So you have a natural delay of how long it will take you to get into it.”

Lastly, REM makes up about 20 to 25 percent of your nightly sleep and mostly takes place in the second half of the night. “If you cut your sleep short, most of what you’re cutting out is REM,” says Grandner. “And too little REM sleep can leave you feeling groggy, less able to focus, and might lead to memory problems.” That’s why it’s important to get enough rest after learning something new or before taking an exam. Many medications can also block REM. “Most antidepressants can cut REM sleep by half,” says Grandner.

Consistently getting too much REM could also create problems. “If you go too much over 25 percent of REM, it might cause too much brain activation, which can leave you angry and irritable and can even potentially exacerbate depression and anxiety symptoms,” says Grandner. 

Wake Up Happier and More Refreshed

When analyzing your sleep-stage data, keep in mind that the percentages above are based on broad averages. To compare your stats to the averages of others who are the same age range and gender, click the sleep tile on your dashboard and then choose “Benchmark.” (In the graph, the normal range for each sleep stage is shown as the shaded area between the two horizontal lines.) Even then, though, both Grandner and Siebern urge you to note that every individual has different sleep needs.

Fitbit sleep stages benchmark
“Everybody’s a little different,” says Grandner. “As long as you give yourself enough time to sleep, and you don’t have any kind of sleep disorder that’s keeping you out of any certain stages of sleep, your body will figure it out using it’s own rhythms and drives.”

Siebern agrees: “We can do things to help improve the quality of our sleep, but we all have a baseline that determines how much of each sleep stage we’ll get.” (Check out these 8 Tips for Getting a Good Night’s Sleep.) There really is no ideal.

“Ideal is whatever your body does given enough of an opportunity,” says Grandner. Ask yourself, suggests Siebern, how you feel. If your sleep stages are falling outside the averages but you feel refreshed and engaged, then you’re likely getting the quantity and quality of sleep you need. Use that as your baseline by which to compare future sleep sessions.

134 Comments   Join the Conversation

134 CommentsLeave a comment

    • Do you have an ALTA HR? I do, and I just found this info on mine. Go to your sleep tile, then choose any night’s sleep on the far right. It will bring up the percentages & the benchmark selection

      • I spent probably upwards of 5 minutes looking for the “Benchmark” tab. Important point #1, it doesn’t exist on my computer application. I can click on the sleep data for last night, for example, and see the cool graph breaking down REM from deep sleep, etc. but there’s no “Benchmark” tab. I’m not sure Fitbit listens or cares, but it would be *great!* if this function existed on the desktop app. Important point #2, I had to update the phone app, delete the version I had and open the updated version to get access to the mysterious “benchmark” tab. When using your phone and you have the Fitbit app open, click on the sleep tile. See where it says “This Week” and below that is “Today.” There is a graphical representation of your sleep last night. Touch that.This will open the cool “Sleep Stages” graph page. Below the graph is “Time Asleep” and below that is “Sleep Stages.” Below that is a button bar with 3 choices: it’s defaulted to “Today” but your other two choices are “30 Day Avg” and “Benchmark.” Simple, right ( 🙁 ). Anyone could intuit that… What I’d like to see added are choices like customers get in Premium where the user can compare their sleep to either sex and various age ranges.

  • I have been having sleep apnea for over a year now and have seen several doctors, which greatly helped in my recovery process. They’ve been explaining things that I have not fully understood – so thank you for this blog post. Somehow it all makes sense now!

  • Why isn’t this available for all fitbit devices? I have a fitbit Flex 2, which is a new recently released device, and your not going to support it with updated features?

  • I see on March 6th CallieFitbit announced the introduction of Sleep Stages on the forum but I don’t see anything for Stages on my Blaze. Am I missing something???

  • I see on March 6th CallieFitbit announced the introduction of Sleep Stages on the forum but I don’t see anything for Stages on my Blaze. Am I missing something???

    • So, I had the sleep stages show up for ONE night and then … no more. What gives? A response from those in the know would be very welcome. Thank you.

  • HOw come no one can answer your questions??? I am looking forward for the answer about release date. I am the one has problem with sleep and would love to know whats going on while I sleep. Please answer to their questions with date.

  • The sleep tracker is very wrong. Since I got the Alta, it’s told me that I’m getting approximately 4-5 hrs of good sleep, despite my feeling well rested after 7-8 hours. Last night, I awoke around 4 and was unable to go back to sleep until after 6 and even then my sleep was light. This morning the tracker says I got 7+ hours of sleep. Ridiculous.

  • When will sleep stages be coming for Charge 2? I bought one last night, after reading articles online that I understood as saying it was a currently available feature.

    • I have a charge 2 and the sleep stages are not being recorded. March 27th is several weeks past, am I being too impatient in expecting to see these yet?


  • Why won’t sleep stages be available for all Fitbit Trackers that monitor heart rate? The inaccuracy of sleep tracking on my Charge HR has made me consider buying a competitor’s sleep tracking device instead. Why not let me try out this new feature to see if it works well? It would encourage me to buy more Fitbits instead of switching brands.

  • I’m still waiting for this update…I got a notification about it when I opened my app a few days ago but my sleep is still being tracked the old way….

  • Thinking about LG smartwatch or Fitbit Charge 2 because of this feature. If it not coming out soon. It might just help me make my decision to go with the smartwatch!

  • I had the stages on my blaze for three days and now it reverted back to the old way of showing it. How can I get back to see the stages again?

  • I had this on my dashboard for a few days and now it’s just reverted back to the original non sleep stages version. Any reason why?

    • I thought I was the only one. Actually wondered if I had imagined it. Glad to know I’m not the only one but I do wish someone would let us know what’s going on.

  • I see sleep stages show up in the sleep mode on the app but it says no data available. If it’s in the app, why is it not registering?

    • Same happens to my tracker/app – can some one help with this question? If we have to wait more to see it functioning properly just say so. But it’s unfair to leave everyone hanging with no info …

  • If it is coming in March there is precious little time to complete it. Not working at, Windows 10 or Android 7.0 for me and Charge 2

  • I have s Charge 2. The new sleep data format showed up on my dashboard for three days this week, then disappeared. I would love to get it back? How? When?

  • I really liked this new feature but only had it for a couple days and now it is gone. I would like to know how to get it back please.

  • I absolutely love this new update … really accurate and love how it shows different stages of sleep!! I’m totally hooked on checking it when I wake! Well done Fitbit!! X

  • After a little over a week with the new sleep stage data on my dashboard I woke this morning to the old data.

  • I have a Charge 2 and I just received the update that shows the sleep stages. Love it! I thought the sleep tracking before was pretty useless.

  • Same as others….sleep data showed for one day last week and hasn’t shown up again since. Fairly frustrating but good to know I’m not actually losing my mind ( due to lack of sleep!)The sleep tracker is working very well for me.

  • Can anyone answer why my app shows my sleep stages one day and then reverts to the old sleep display the next and back and forth? I was really excited about this feature when I came back to Fitbit last week, but I’m really disappointed with the inconsistency.

  • Danielle, nice overview of this feature! For the deep sleep category (Non-REM) AASM (American Academy of Sleep Medicine) combined Stages 3 and 4 into just stage 3. Is there any comparison that was done with regards to sleep stages from the Fitbit and from a scored polysomnogram? I would be interested to see how it was validated. I look forward to seeing this on my Charge 2 !

  • I have got sleep stages one night only. Is there something I need to download on blaze for it to be fully functional. Don’t know of anything I did the night I got them different then any other night.

  • How come I could see the sleep stages on my blaze for the past few days and then no more since yesterday? How to activate this?

  • The new sleep patterns do NOT give the Times when you were awake or restless. Go back to the OLD one that tells you WHEN you were awake by the Clock.

  • I have the Fitbit Blaze. The sleep stages showed up for a couple of days and now it is gone. I really liked the information on the sleep stages and seeing how it was broken down. I hope it is back soon.

  • Interesting article and it seemingly works great on my Alta HR. But please correct the distracting grammatical error “its” not “it’s”!

    • Yep, mine too. No sleep stage. What does that even mean. Also, why is no one from Fitbit responding to all of these questions?

  • You know, this would all be fine and dandy if the watch didn’t come on like a beacon every time you twitched. It disrupts sleep several times a night. I’d love to be able to regulate my sleep patterns more but I end up exhausted from too much light pollution from the silly watch!! I’ll pass on your sleep stages for a decent night’s sleep!

  • I have a very unusual sleep disorder that may be helpful in tuning the sleep detection. I get no Delta sleep (stages 3, 4) at all (since age 45 at least). Sleep study and research by high level AAA guy confirmed.
    Yet charge 2 says I get typical deep sleep?! 🙂

    Happy to help if/as possible.


  • Hello,
    I just had an update on my Fitbit charge 2, still no sleep stages available.
    Is there something wrong with the software?

  • So FRUSTRATED. The main reason I purchased my Charge 2 was for Sleep and Heart monitoring. I keep checking my Hours in Sleep stages and although I have updated Firmware, nothing appears.
    Any idea when I can expect to see information.
    I’m unhappy I paid $238 for only 50% of the information I’m now require.
    Everyone purchases for a different reason & everyone has different needs. Maybe you could advise which Tracker I need to purchase, because this one no longer fits my needs. I’m extremely disappointed.
    I posted to the Community Forum, under WHY CHANGE SOMETHING IF IT AIN’T BROKE!

  • I have the charge 2. Sleep stages graph shows up on my app. But they are always greyed out and say stages unavailable. Is it just not fully rolled out? Do I need to restart my Fitbit?

  • Would be extremely helpful if everyone got this feature! I think it’s ridiculous with how successful Fitbit has been and they can’t maker sure an update is updated right. Don’t get me wrong I love mine, but it’s agrevating when my mom gets this update and mine doesn’t… Just saying

  • I have a Charge 2 and instead of sleep stages such as ‘Light’ or ‘Deep’ it only shows me ‘No stages’ every night. I wear my Fitbit to sleep every night, why doesn’t it work?

  • As of 18 Apr 2017, Sleep stages for my wife and her Charge 2 works great, still does not show on my Charge 2….. Every update applied on two identical trackers but one works and one does not…..

  • When will the sleep cycle details be available on Charge 2? As of now only sleep, awake & restlessness are shown on the sleep data.

  • Why does My fitbit charge2 registrate me sleeping everytime I sit down, watch TV and so on…
    is it any thing I did wrong while set the clock up?

  • i brought the fit bit charge 2 so that i could see how much REM sleeping I’m getting and deep sleep, but i’m upset to see after days of trying to work it out that apparently my phone, samsung A5 is not compatible. feel like i’ve wasted my money now

  • My Fitbit blaze showed sleep stages one morning only, then went back to the old way. How do I change it to show stages everyday?

  • I bet we all want a release date. But they aren’t giving any information away. Other than – you’ll get it when you get it. Downright annoying, fitbit.

  • I bought a new Fitbit Altria 2 primarily for the sleep function it had shown up once in a month, it just plain and simple does not work

  • I have a FB 2 and the new “stages” feature appeared Friday night. Great information. Then I did an update yesterday and the “stages” disappeared last night. How do I get it back?

  • I have a FB Charger 2 and the new “stages” feature appeared Friday night. Great information. Then I did an update yesterday and the “stages” disappeared last night. How do I get it back?

  • I had 2 nights of sleep cycle data and then it has gone back to the old format with just lines. How do I continue to get sleep cycle data?

  • My Fitbit charge 2 showed sleep stages on only 2 nights, yesterday and the night before. Today it doesn’t show my sleep stages.

  • So many articles on sleep stages and other sleep issues! But I couldn’t find a good article what to do when you are chronic insomniac and have a baby who keep waking up for feeding.

  • Love my new Alta HR. Very disappointed however that the age/gender normed sleep stage benchmarks are only available with a premium subscription – something you failed to mention but which was explained by Annaliza D on your Fitbit Support Team when I couldn’t make your instruction work. Since I am not interested in other “benefits” of the Premium subscription, I will just have to do without that data. I hope you soon make this available to all or change your narrative.

  • The different stages showed on my Charge 2 for 3 days and has now reverted back to the old sleep pattern. When will they be coming back? I found the new info very useful!

  • I love the new feature with the different sleep stages. As I read all the comments above my post it still need some improvement on it stability. The new version also showed only onces on my charge 2 and now it is back to the old version. Hope it will be fix soon, the sneak preview of the new version looked very good!

  • I have a Charge2 that has only provided the new “stages” 3 times since I purchased 12/16. I have the most recent update on my iphone. What do I need to do to get this accurate information? This is the main reason I purchased the fitbit to monitor my sleeping that is not sufficient at this time. The retailer would not stand behind the product after 30 days. Does this mean I would not to incur the cost to ship back for replacement if that becomes necessary? Please provide me with some solid information, thanks.

  • My Fitbit recorded my sleep great the first two nights and now it doesn’t kick in until 3 am? I’m going to bed at 11pm. Do I need to return my Fitbit?

  • I have a charge 2 and I had the sleep stages appear the first two nights I used it (Sunday and Monday), but since then the last three nights it has not worked and shows no stages. I keep the band tighter than normal and it’s still not working. How can we fix this???

  • Just getting used to my new monitor I can see them used for patients with memory issues or maybe a button for where is mom? Will be next or for a beeper ( like black box ) when trying to find a lost kid. Keep up the good work Fitbit, love ya

  • I have a Fitbit Charge 2 and am unable to find the benchmark for sleep patterns discussed in the article. Any ideas? Thank you.

  • I love the new format, it is most useful … BUT, it revert to old format for me the last 3 days … I checked the heart rate tracking, it shows it’s being recorded, so that’s not the problem. I also checked battery level, it’s above 50%, not that either. So, wonder what I did to mess it up?

  • I bought my Alta HR a week ago and it has worked every night giving me sleep stages. This article was very helpful in understanding the different stages.

  • Mine worked for one night and than stopped. Can someone tell me how to fix it? I’ve looked through the entire app and can’t figure it out

  • My Fitbit has stopped telling me how much time was spent in each stage of sleep.
    It only shows the quality of sleep now.

    I have the charge 2

  • I love this feature on my new Charge 2. Yesterday morning, when I checked my sleep cycle, it had reverted back to the old format. I can’t figure out how to get the REM, deep sleep, light sleep, and awake patterns to reappear on my sleep report. Can someone help?

  • My husband goes into deep sleep twice already which is so scary. He uses CPAP & at first I thought it has a relation when he took off his CPAP the first time. But the second time it happened with his CPAP on. Is there any possibility of treatments on this condition ?

  • My sleep display just shows some bunched up lines in the beginning, then nothing shows up again until morning with a few more bunched up lines. Does not look at all like the sample. Is anyone else having this issue? And how can I fix it?

  • This is quite interesting about R.E.M sleep!
    I’ve been having seizures for 9 yrs due to electric shocks in my hypocampus (the part of the life side of your brain).. causing seizures a few time a day & night & due to a surgery removing a third of the hypocampus 3 yrs ago, I only I have 1-2 seizure per night. The recebt test I’ve done is they found I don’t R.E.M sleep. Not certain how my Drs & I haven’t found a solution as of yet.
    Any ideas?

  • I have the fitbit Alta HR and notice my REM sleep is only about an hour a night or less. My deep sleep is only average 30 min. and my light sleep averages 5.5 to 6 hours. I am often tired and cranky when I get up. Is there a way to increase the deep and REM cycles? Is anyone familiar with Pink Noise and how well that works. I am awake many times during the night anywhere from 4-6 times for a total of 1-2 hours

  • What does no stages mean? Apparently I only get maybe one night a week that shows those stages but the rest say no stages.

  • Great article. Thank you! I’m amazed at the features of my Fitbit Blaze. It’s sleep capabilities are fantastic and far superior to my husband’s Apple Watch. In fact, Apple doesn’t have a built in sleep feature and we’re having trouble finding an app that even comes close to the quality of data I’m getting on the Fitbit Blaze!

  • Hoe does Fitbit measure the stages of sleep when only measuring heart rate and movement?
    Has Fitbit’s interpretation been validated in a peer reviewed medical journal.
    Is it registered as a medical device?

  • My mother -in- law (68) gets between 6.5 and and 7.5 hours of “Deep Sleep” each night. How is this possible? I’ve spent the last 3 hours reading up on the stages of sleep from multiple sources and can’t find any information on her Super Human Deep Sleep skill. I’ve been tracking my sleep cycles for a couple years now, i just don’t understand how she gets SO much deep sleep. How is this impacting her life? She’s not making the best choices these days. I expected to find sleep depervation not the exact opposite.

  • Can only sleep for about 4.5 to 5 hours. Not tried and can go all day .
    went to sleep clinic for cause.Dr said I went into REM after 30 mins of sleep and got a very high percentage of time was Rem .He stated I got more Rem time than Avg. He also stated they see this in a few patients and said I was lucky.
    I should add I dream every night and I remember them. Any comments?

  • I’ve developed a sleep pattern over the past few weeks that puzzles me.. I wake every three hours exactly and would like to know doesn’t matter what time I go to sleep I still continue to maintain the three hourly rythme.
    .Any ideas? thanks

  • Just be aware that the reading you get on any of these devices wont be 100% accurate. I have 2 sleep disorders but my fitbit shows that my sleep patterns are normal. To get an accurate reading and assessment of your sleep quality you need to get brainwave readings, heart rate and measure breathing. You need to have electrodes attached to your head and body. These watches only measure your heart rate. if you have any concerns about your sleep quality please see a sleep specialist. If you are using a Fit Bit or similar for curiosity, then go for it.

  • My Charge 2 stopped showing sleep stages after only one day out of seven. I know my resting HR. Is low due to medication. Is this the possible reason? Is there fine tuning to the app?

  • Hello fitbit newsletter editor:
    As a fitbit user I have no idea how to set the time on my fitbit after a period of inactivity and loss of battery power. I called your helpline and a technician guided me through the many steps to set the correct time. However, after sometime due to a dead battery I lost the time again and am wondering if there is an easy step-by-step guide that is available from fitbit that can guide me to reset my time.
    Please help.
    Thank you,

  • I have a FitBit Charge 2. On my dashboard, when I click on my sleep line, it defaults to showing today and does not have “30 Day Average” or “Benchmark” available to click as stated in this article. Does that feature only apply to certain FitBit models?

  • In Nov ’17 I purchased a Fitbit Alta HR specifically to track sleep stages. For the first 5-7 nights it worked fine but since then has fairly accurately traced time and hours of sleep only. I’ve followed all directions I can find way to correct this problem including tightening and loosening the band, switching arms etc. all to no avail. A another long time user did a complete reset and reinstall and that hasn’t solved it. HELP!

  • I have FitBit Alta HR, just setup yesterday, so I only have 1 night’s sleep saved. Prior, I had a FitBit One, with a couple year’s worth of sleep history saved. I expected the nights tracked with the AltaHR to have the new sleep stages, but all I see is the old style “Asleep / Restless / Awake” stats – none of the new REM/light/etc. What gives?

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