Why Do We Need Sleep?

A healthy diet and positive lifestyle habits can help ensure an adequate amount of sleep each night – but for some, chronic lack of sleep ... Opensinanewwindow Share: Home /HowSleepWorks /WhyDoWeNeedSleep? WhyDoWeNeedSleep? UpdatedMarch11,2022 Writtenby DaniellePacheco,StaffWriter MedicallyReviewedby Dr.AbhinavSingh,SleepPhysician FactChecked Ourdedicatedteamrigorouslyevaluateseveryarticle,guide,andproducttoensuretheinformationisaccurateandfactual.LearnMore Ourdedicatedteamrigorouslyevaluateseveryarticleandguidetoensuretheinformationisfactual,up-to-dateandfreeofbias. InThisArticle TheScienceBehindSleep HowMuchSleepDoHumansNeed? TheImportanceofGettingEnoughSleep Ourmedicalreviewteamhasrecentlyevaluatedthispagetoensureaccuracy.Wewillcontinuetomonitorandrevisethisarticleasnewliteratureispublishedontheimportanceofsleep. Sleepisanessentialfunctionthatallowsyourbodyandmindtorecharge,leavingyourefreshedandalertwhenyouwakeup.Healthysleepalsohelpsthebodyremainhealthyandstaveoffdiseases.Withoutenoughsleep,thebraincannotfunctionproperly.Thiscanimpairyourabilitiestoconcentrate,thinkclearly,andprocessmemories. Mostadultsrequirebetweensevenandninehoursofnightlysleep.Childrenandteenagersneedsubstantiallymoresleep,particularlyiftheyareyoungerthanfiveyearsofage.Workschedules,day-to-daystressors,adisruptivebedroomenvironment,andmedicalconditionscanallpreventusfromreceivingenoughsleep.Ahealthydietandpositivelifestylehabitscanhelpensureanadequateamountofsleepeachnight–butforsome,chroniclackofsleepmaybethefirstsignofasleepdisorder. TheScienceBehindSleep Aninternal“bodyclock”regulatesyoursleepcycle,controllingwhenyoufeeltiredandreadyforbedorrefreshedandalert.Thisclockoperatesona24-hourcycleknownasthecircadianrhythm.Afterwakingupfromsleep,you’llbecomeincreasinglytiredthroughouttheday.Thesefeelingswillpeakintheeveningleadinguptobedtime. Thissleepdrive–alsoknownassleep-wakehomeostasis–maybelinkedtoadenosine,anorganiccompoundproducedinthebrain.Adenosinelevelsincreasethroughoutthedayasyoubecomemoretired,andthenthebodybreaksdownthiscompoundduringsleep. Lightalsoinfluencesthecircadianrhythm.Thebraincontainsaspecialregionofnervecellsknownasthehypothalamus,andaclusterofcellsinthehypothalamuscalledthesuprachiasmaticnucleus,whichprocessessignalswhentheeyesareexposedtonaturalorartificiallight.Thesesignalshelpthebraindeterminewhetheritisdayornight. Asnaturallightdisappearsintheevening,thebodywillreleasemelatonin,ahormonethatinducesdrowsiness.Whenthesunrisesinthemorning,thebodywillreleasethehormoneknownascortisolthatpromotesenergyandalertness. StagesofSleep Oncewefallasleep,ourbodiesfollowasleepcycledividedintofourstages.Thefirstthreestagesareknownasnon-rapideyemovement(NREM)sleep,andthefinalstageisknownasrapideyemovement(REM)sleep. Stage1NREM:Thisfirststagemarksthetransitionbetweenwakefulnessandsleep,andconsistsoflightsleep.Musclesrelaxandyourheartrate,breathing,andeyemovementsbegintoslowdown,asdoyourbrainwaves,whicharemoreactivewhenyouareawake.Stage1typicallylastsseveralminutes. Stage2NREM:ThissecondNREMsleepstageischaracterizedbydeepersleepasyourheartrateandbreathingratescontinueslowingdownandthemusclesbecomemorerelaxed.Eyemovementswillceaseandyourbodytemperaturewilldecrease.Apartfromsomebriefmomentsofhigherfrequencyelectricalactivity,brainwavesalsoremainslow.Stage2istypicallythelongestofthefoursleepstages. Stage3NREM:Thisstageplaysanimportantroleinmakingyoufeelrefreshedandalertthenextday.Heartbeat,breathing,andbrainwaveactivityallreachtheirlowestlevels,andthemusclesareasrelaxedastheywillbe.Thisstagewillbelongeratfirstanddecreaseindurationthroughoutthenight. REM:ThefirstREMstagewilloccurabout90minutesafteryoufallasleep.Asthenamesuggests,youreyeswillmovebackandforthratherquicklyunderyoureyelids.Breathingrate,heartrate,andbloodpressurewillbegintoincrease.DreamingwilltypicallyoccurduringREMsleep,andyourarmsandlegswillbecomeparalyzed–it’sbelievedthisisintendedtopreventyoufromphysicallyactingoutonyourdreams.ThedurationofeachREMsleepcycleincreasesasthenightprogresses.NumerousstudieshavealsolinkedREMsleeptomemoryconsolidation,theprocessofconvertingrecentlylearnedexperiencesintolong-termmemories.ThedurationoftheREMstagewilldecreaseasyouage,causingyoutospendmoretimeintheNREMstages. Thesefourstageswillrepeatcyclicallythroughoutthenightuntilyouwakeup.Formostpeople,thedurationofeachcyclewilllastabout90-120minutes.NREMsleepconstitutesabout75%to80%ofeachcycle.Youmayalsowakeupbrieflyduringthenightbutnotrememberthenextday.Theseepisodesareknownas“W”stages.   HowMuchSleepDoHumansNeed? Therightamountofsleeplargelydependsonyourage.TheNationalSleepFoundationrecommendsthefollowingdailysleepallotmentfordifferentagegroups. AgeGroup AgeRange RecommendedAmountofSleepperDay Newborn 0-3months 14-17hours Infant 4-11months 12-15hours Toddler 1-2years 11-14hours Preschool 3-5years 10-13hours School-age 6-13years 9-11hours Teen 14-17years 8-10hours YoungAdult 18-25years 7-9hours Adult 26-64years 7-9hours OlderAdult 65yearsorolder 7-8hours TheImportanceofGettingEnoughSleep Formostadults,atleastsevenhoursofsleepeachnightisneededforpropercognitiveandbehavioralfunctions.Aninsufficientamountofsleepcanleadtoseriousrepercussions.Somestudieshaveshownsleepdeprivationleavespeoplevulnerabletoattentionlapses,reducedcognition,delayedreactions,andmoodshifts. It’salsobeensuggestedthatpeoplecandevelopasortoftolerancetochronicsleepdeprivation.Eventhoughtheirbrainsandbodiesstruggleduetolackofsleep,theymaynotbeawareoftheirowndeficienciesbecauselesssleepfeelsnormaltothem.Additionally,lackofsleephasbeenlinkedtoahigherriskforcertaindiseasesandmedicalconditions.Theseincludeobesity,type2diabetes,highbloodpressure,heartdisease,stroke,poormentalhealth,andearlydeath. Adultswhodonotreceiveasufficientamountofsleepeachnightcanimplementsomepositivelifestyleandsleephabitsinordertologtheneededseventoninehours.Theseincludethefollowing: Establisharealisticbedtimeandsticktoiteverynight,evenontheweekends. Maintaincomfortabletemperaturesettingsandlowlightlevelsinyourbedroom. Keepacomfortablesleepenvironmentbyensuringyouhavethebestmattress,bestpillows,andbestsheetsforyoursleeppreferencesandbodytype. Considera“screenban”ontelevisions,computersandtablets,cellphones,andotherelectronicdevicesinyourbedroom. Abstainfromcaffeine,alcohol,andlargemealsinthehoursleadinguptobedtime. Refrainfromusingtobaccoatanytimeofdayornight. Exerciseduringtheday;thiscanhelpyouwinddownintheeveningandprepareforsleep. Wasthisarticlehelpful? YesNo AboutOurEditorialTeam DaniellePacheco StaffWriter Daniellewritesin-deptharticlesaboutsleepsolutionsandholdsapsychologydegreefromtheUniversityofBritishColumbia. Dr.AbhinavSingh SleepPhysician MD Dr.SinghistheMedicalDirectoroftheIndianaSleepCenter.Hisresearchandclinicalpracticefocusesontheentiremyriadofsleepdisorders. Share: References +7 Sources 1. Berger,F.,Zieve,D.,&Conway,B.(2020,August4).SleepandYourHealth.MedLinePlus.Retrievedfrom https://medlineplus.gov/ency/patientinstructions/000871.htm 2. NationalInstitutesofHealth.(2019,August13).BrainBasics:UnderstandingSleep.NationalInstituteofNeurologicalDisordersandStroke.Retrievedfrom https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/understanding-Sleep 3. NationalCenterforChronicDiseasePreventionandHealthPromotion,DivisionofPopulationHealth.(2020,March20).AreYouGettingEnoughSleep?CentersforDiseaseControlandPrevention.Retrievedfrom https://www.cdc.gov/sleep/features/getting-enough-sleep.html 4. NationalHeart,BloodandLungInstitute.(n.d.).SleepDeprivationandDeficiency.RetrievedAugust20,2020,from https://www.nhlbi.nih.gov/health-topics/sleep-deprivation-and-deficiency 5. B.,R.,&Born,J.(2013).AboutSleep’sRoleinMemory.PhysiologicalReviews,93(2),681–766.Retrievedfrom https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768102/ 6. Schwab,R.(2020,June).OverviewofSleep.MERCKMANUAL.Retrievedfrom https://www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/sleep-disorders/overview-of-sleep 7. Eugene,A.,&Masiak,J.(2018).TheNeuroprotectiveAspectsofSleep.MEDTubeScience,3(1),35–40.Retrievedfrom https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651462/ LearnmoreaboutHowSleepWorks HowSleepWorks UpdatedBy EricSuni | April1,2022 HowYourBodyUsesCaloriesWhileYouSleep By DaniellePacheco | April1,2022 MemoryandSleep By DaniellePacheco | March11,2022 SleepDebtandCatchingUponSleep By RobNewsom | April1,2022 HowElectronicsAffectSleep By DaniellePacheco | April1,2022 Infographic:ElectronicsandSleepintheModernFamily By TheNationalSleepFoundation | April12,2022 SleepandSocialMedia By RobNewsom | March11,2022 CBDasaSleepAid By DaniellePacheco | March11,2022 MoonPhasesandSleep By SarahShoen | March11,2022 Oversleeping By AustinMeadows | March15,2022 HypnopompicHallucinations By TomRyan | March11,2022 HypnagogicHallucinations By TomRyan | April11,2022 LightSleeper:WhatItMeansandWhatToDoAboutIt By DaniellePacheco | March11,2022 BiphasicSleep:WhatItIsAndHowItWorks By SarahShoen | April6,2022 PolyphasicSleepSchedule By DaniellePacheco | March11,2022 SleepInertia By DaniellePacheco | March11,2022 SleepLatency By DaniellePacheco | March11,2022 SleepSpindles By JaySummer | March11,2022 Microsleep:WhatIsIt,WhatCausesIt,andIsItSafe? 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By DaniellePacheco | April1,2022 SleepDictionary By EricSuni | March11,2022 SleepStatistics By EricSuni | March11,2022 LoadMoreArticles OtherArticlesofInterest SleepHygiene SleepTips-HowtoSleepBetter LearnAboutSleepHygiene HowtoRelieveStressAtBedtime HowtoImproveSleepQuality HowMuchSleepDoYouNeed? BedroomEnvironment HowtoCreateTheIdealBedroomEnvironment LightandSleep WhatIsWhiteNoise? TechnologyInTheBedroom HowDoesMusicAffectSleep? 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