ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Tips Sleep

Updated on April 28, 2010

What happens while we are sleeping and why do we need to sleep?

What is sleep?

We all know we need it and suffer when we don't get enough, but what is sleep and why do we need it? Some people have likened sleep to a complete shut down, like turning off a computer. However, sleep is more like a prolonged "re-boot" where files are put into order. It is difficult to describe exactly what sleep is, but it is an active process and is essential for growth, repair, memory, and ultimately, life.

What happens during sleep?

Most adults function best on 7 or 8 hours sleep each night, although some people need more and some less. As long as you feel rested and awake when you need to be, you are probably getting enough sleep1.

Sleep is a biological need for all animals. It helps us to rest and recuperate physically and psychologically, and to grow and regenerate body cells. Some scientists believe that sleep plays a role in developing memories2.

The biological clock

Our levels of sleepiness and wakefulness are partly regulated by our biological clock, which increases certain chemicals in our body to make us feel more or less awake, and external stimulus factors such as night and day. Difficulties in sleep arise when our body clock is disrupted and forced to work in an inappropriate way, for example, during shift work or when suffering from jet lag.

What are sleep cycles?

Sleep has many layers and stages but the most important division is between REM (Rapid eye movement) and NREM (Non-rapid eye movement) sleep1. A sleep cycle is composed of both REM sleep and NREM sleep.

REM sleep - REM stands for rapid eye movement, because your eyes periodically move rapidly during this sleep stage, where brain activity is high. It is also when you dream. Your muscles become temporarily paralyzed during this kind of sleep to prevent you from acting out your dreams.

NREM sleep - During NREM (non-rapid eye movement) sleep, brain activity is much slower. However, you are able to move more naturally, and it is during this stage that sleepwalking and talking take place. Research suggests that rest and restoration also take place during this time.

NREM sleep is divided into four stages. During the night you pass through these different stages from light sleep in stage 1 and 2, to deep, restorative, slow-wave sleep in stages 3 and 4. The amount you spend in each stage of sleep varies depending on your sleep need and usual sleep pattern. You move up and down in these four stages during the night and find it much easier to wake up if disturbed during phase 1 than during phase 4.

How do sleep cycles work?

Each cycle of NREM and REM lasts approximately 90 minutes. At the end of each cycle you wake up, but often without realizing it, because your brain encourages you to go back to sleep immediately to start a new cycle. Most people are not aware that they woke up during the night, however some people do remember this. This isn't a problem, unless you wake up and stay awake. In total, adults spend about 20 percent of the night in REM sleep, while babies spend about half their time in REM sleep.

Test - how long is your sleep cycle?

You can find out how long your own sleep cycle is with an easy experiment. Next time you are forced to stay awake past your natural sleeping time, for example, at a social occasion or if you have to work very late, and you are feeling so tired that you could fall asleep, record the time. If you stay awake through this time, in about 15-20 minutes you will start to perk up again and feel more alert. However, the feelings of extreme tiredness will return - the time between your first strong feelings of tiredness and your next wave of tiredness is your sleep cycle. Most people have a cycle of about 90 minutes.


  1. Dement W. The promise of sleep. Macmillan. 1999
  2. Idzikowski C. Insomnia. Newleaf. 1999 
  3. National Institute of Neurological Disorders and Stroke (USA). Brain basics: understanding sleep. 2000; 
  4. Sleep Home Pages. Basics of sleep behavior. Part A. What is sleep-1998;
  5. Pritzker School of Sleep Medicine, University of Chicago.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)