Why Do You Even Need Sleep?


Right up there with functions like breathing and blinking, sleeping is an activity you totally take for granted. If you’re like most people, you go about your daily routine. You go to work, go to lunch, go home, pick up the kids from soccer, work out—and eventually pass out.

And little do you know, your body is doing a major overhaul and recharge every time you catch some zzz’s. It affects every system of the body, your emotions and mood, how well you think and how well you perform.

“In general, sleep is critical for survival,” says Michael Smith, PhD, Director of the Behavioral Sleep Medicine Program at Johns Hopkins University and a sleep insights consultant for Fitbit. “Almost every living thing has some form of rest, and almost every bodily process benefits from sleep.”

Interestingly, scientists still aren’t exactly sure why humans have adapted to sleep. There are theories, like early research that shows sleep might be the body’s way of eradicating a buildup of waste from the brain. When you hit the sack, the space between brain cells is flooded with cerebrospinal fluid. This seems to “clean” the brain, “sweeping away the detritus of the day,” Smith explains.

There’s also research linking sleep loss and sleep disorders to a myriad of health issues, which offer clues as to why this basic activity is so essential. The link to heart disease suggests sleep may have evolved as a way of relieving vascular stress. The link to depression hints that sleep may a way of dealing with emotionally overwhelming situations.

The research linking a lack of sleep to lower performance across the board is astounding. “Sleep optimizes how your brain works,” Smith says. “There are studies that show sleep helps to regulate emotions and mood. Sleep is also essential for attention, concentration and executive function, which helps us make good judgments, remain flexible and creative.”

On the physical side, sleep is involved in almost every physiological process, says Smith. “Sleep regulates how the body controls pain. Lack of sleep is stressful, causing higher blood pressure and heart rate—and it can also alter metabolism, leading to spikes in blood sugar that can cause insulin resistance. There’s even research to show those who don’t get enough sleep develop the common cold at much higher rates.”

Bottom line? Sleep is one of the most mysterious, overwhelmingly important vital functions living beings have evolved to participate in. You need it. A whole lot. “Even partial sleep deprivation can impair things like cognition, memory, and overall functioning,” Smith says. “You can get used to it, and think you’re doing okay—yet you’re really not performing at your best.”

Everyone could stand to self-evaluate their personal sleep habits, since a whole lot of people are currently suffering from insomnia or what science has termed “Insufficient Sleep Syndrome”—which is exactly what it sounds like.

Here’s how to determine if you’re getting enough sleep, according to Smith:

Check the general guidelines

Smith says this is the best place to start for determining how much sleep you need, because everyone is slightly different. In general, adults need roughly seven to eight hours of sleep per day. Super-far from that? It’s time to make some adjustments. (Check the CDC chart if you have teens, kids or babies in the house.)

Determine the right amount of sleep for you

Smith says the best way to figure out exactly how much sleep you need per night is to test it out on a week of vacation. “Start by adding an extra half hour to your night, a little more if you feel you need it,” he says. “You should begin to feel the difference in your body, your thinking.” Plus, a good week of sleep can do a lot to help you begin to feel substantially better if you’ve been accumulating a lot of sleep debt.

Watch your habits

If you need to caffeinate multiple times throughout the day to stay functional, your focus and attention starts to wane well before working hours end, or you’re excessively sleepy (perhaps actually falling asleep during those afternoon meetings), you’re not getting enough sleep. Every little bit helps. Smith says to try tacking on just 15 or 20 minutes to your nightly sleep—which can add an extra couple hours of rejuvenation to your weekly total.

Avoid crazy fluctuations 

To sleep in, or not to sleep in? Although advice is mixed, Smith says it’s completely fine to give yourself a couple hours of additional shuteye on the weekends if you’re running on E. “Avoid drastic fluctuations if you have chronic insomnia, though, since routine can help in that instance,” says Smith. Wild swings can toy with your circadian rhythm, and make sleep even harder than it already is, he says.

Keep in mind: it’s also possible to overdo your rest. Get 12 hours of sleep on Saturday or Sunday, for example, and you could be setting yourself up for a restless week. Stick to an extra hour or two max on your weekend days, and you’ll be in better shape for the next five wake-up calls. As with almost everything, maintaining a balance is best.

If you’re meeting these guidelines and still feel tired all the time, be sure to consult your physician. She can help you take a deeper look at your sleep situation and determine the next best steps for you.  

71 Comments   Join the Conversation

71 CommentsLeave a comment

  • Duration of sleep changes with the ages. Can any one help me in this respect ? How many hrs sleep is required for a man of 70?

  • I would like to know about what is normal for restless during sleep. Fir example I got 9 hrs of sleep 7
    Restless. Is that normsl etc.

  • Phyl. I’m no sleep expert but 7 hours of restless sleep does not sound good. Is that what your Fitbit is indicating? Are you in pain? Is your mattress comfortable?

  • I appreciate seeing the advice to talk to my doctor. Sleep apnea can be a real problem, hours in the sack and no real rest. Mine is mild, a splint is sufficient, but if CPAP was indicated I would hate it but do it. Sleep well y’all!

  • I find that eating too late and possibly what you eat can affect good sleeping results. Try not eating later than 7:00 pm NOTHING
    Maybe warm milk, but no chocolate! caffeine is the culprit!


  • How does an afternoon nap for adults play into this? I try to find a place to take a (15-60 minute) nap, especially when I didn’t get enough sleep the night before.

  • As a psychology major sleep is a hot topic that I have had the pleasure of researching–sleep is important! Gotta give props to Ms. Jenna for knowing her stuff when it comes to sleep! The Insight and tips she gives in her post is lagit — I would say more things but I need to sleep now! Sleep tight Fitbiters!

  • My Fitbit Blaze says I slept 5 hours 46 mins
    1x awake 12x restless
    What exactly does that mean?
    What do I do with that information?

  • I suggest everyone who wants to know about sleep and what it does for you, go to ASP Amon Ray or http://www.sleepassessment.com. When there, go to About Sleep and then to Frequently Asked Questions. Martin Gremlich is fantastic concerning sleep. He describes everything in detail.

  • Hi I just read the article about sleep. I am 82 years “young” and have had my Fitbit one since last March. I walk about 12,000 steps most days. But have always had trouble sleeping. I was raised on a farm & blame lack of sleep on growing up on FARM Time. Early am 6am & workmall day & night. ( in the barn, gardens, & hay fields. Not much sleeping.. so I say my biological clock is still on farm time. I am still up at 6am & no naps, & bed time about 10ish pm. And I toss n turn in bed til midnight most nights. I do admit since I started walking I do sleep sooner now & soundly. I’d like to take advantage of the sleep mode on my Fitbit just to see how much I really do sleep. But don’t dare set it up for fear I will loose what information I already have on my Fitbit.

  • My new Charge 2 auto sleep tracking is not accurate! What can I do? Usually the wake up time is an error saying I sleep later than I actually do!

  • I just received the Fitbit as a gift from my son. I am fascinated by this device! I read the article and found many answers to my problems. I am a 61 years old High School teacher who stay up late to grade papers and wake up early to be at school at 7: 40 every morning. This little device will help me a lot in tracking my sleep.

  • Bello, if I hace bought this decide un mundo country why don’t you erige this articule un mundo language?

  • “…sure to consult your physician. She can help you take a deeper look at your sleep situation…”

    Was a bit startled to see it’s a ‘SHE’ instead of a ‘THEY’. Any reason the physician can’t be a guy?

  • Just started my Fitbit yesterday and last night I had 8+hours of sleep with 10 restless times and one time awake. How bad is this?

  • Many people may be suffering from OAS it could be mild moderate or severe. It’s becoming an epidemic and as we learn more about it and the whole health effect it has on the body it is a life changer sometimes saver. There are easier ways to now screen for this and even be tested in your own home. https://g.co/kgs/JMpVVY

  • I don’t like to wear anything on my wrist or fingers when I sleep so I have not utilized the feature. Is there anything else that I could use to monitor my sleep?

  • This is fascinating to me that it shows your sleep pattern….I just got this a week ago…and for years I’ve been aware that I astral project while I’m “asleep” and it’s really cool that the Fitbit picks up on that!

  • Kind of hard to get regular sleep when you work 12 hr shifts and rotate days and nights in the same week. 4 to 6 is about all I get.

  • This text assumes that one could easily decide when and for how long I could sleep. Just like an TV or radio. Unfortunately I am not working that way 🙁 I do fall asleep not that bad but once I wake up in the morning (many times around 4-5) I can’t fall asleep again, even if I’m tired. Usually I’m happy if I get 6-7 hours sleep per day. Then I’m feeling okay, just a bit tired. Though I do know how my body feels after REAL good deep long sleep – a feeling like I would have super powers. Unfortunately I do have this situation only a very few times a year. Many times I just can’t stop my brain and many times I have backaches after six hours of sleep… :-/ that’s the way it is in my life.

    • I know how you feel Peter. I need an on/off button for my brain then I am sure sleep would come to me. If I go to bed I am normally awake for hours as can’t stop thinking about should i’s ,can i’s, did i’s ect. If I snuggle on sofa with crap on tv I can knod off. Very broken sleep but some is better than none.

  • Well I work shifts. And I only ever sleep for bout 3/4 hours a day.but it is not all in one lot.can not sleep mich more .have any one got any good suggest anything to help.

  • +I have a fitbit but there are things I don’t about or how to set-up.
    Where do I go to get help? Please reply back to me.

  • I have sleep apnea and use a sleep machine every night. Have used it for about 14 months. I am still struggling for that good night’s rest and sleep.

  • Does Sleep Stages work on my computer app? I have uninstalled most of my phone apps…it is best for mental health in my case to unplug from all this extra distraction! I hope it is not just for the phone app

  • I used to have the sniffles and a slight cough all the time. My social judicial recommended a minimum of 6 hours sleep and I was cured. I was used to sleeping 3-5 hours nightly. That change made a huge difference.

  • Most doctors will tell you that when you rest and relax your body repairs. We live in a time where we have our foot on the gas most of the time. It;s got to be a good thing to hit the brakes for at least a few hours every 24 hours.

  • My fit bit said I slept 8 hrs, however I went to bed at 1130. Up every 2 hrs.up at 430. How’s this correct. No way I got 8 hrs. Is there a way to ck how sound or how good you’re sleeping?

  • From the time I was a baby, I slept from 3 hours to 5 hours, with naps off and on all day, totaling perhaps 6 to 7 hours, never 8 unless I have a few drinks. Did that in the navy, drove them nuts. ALL my Doctors tell me I need more, and want to give me pills.
    I am now 74, and I feel just fine. What’s up with that?

  • I wish that I could get a decent night’s sleep. I go to bed every night at 10:00. Four days a week, I get up at 4:00 because I work 10 hour days. The other three days, I get up at 5:00 because I work 8 hour days at my other job. I am rarely tired during the day and rarely need the alarm clock to wake me up in the morning.

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