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Take that Nap! It May Boost Your Learning Capacity Among Other Good Things.

Any­one who knows me knows that my favorite pas­time is nap­ping. In Col­lege, I would come back to my dorm room, and like clock­work, would take a nap. My best friend in Eng­land, who got quite a kick out of my pas­sion for nap­ping, once tried to per­suade me to drink a cup of tea after lunch instead of tak­ing my cus­tom­ary nap. I real­ly tried, but I soon gave in to my nap crav­ings. Some­times I feel like I real­ly need to re-charge my brain bat­ter­ies.

Well, now sci­ence is on my side. I just love this new study, which was pre­sent­ed by Matthew Walk­er, assis­tant pro­fes­sor at UC Berke­ley, at the annu­al meet­ing of the Amer­i­can Asso­ci­a­tion of the Advance­ment of Sci­ence (AAAS) con­fer­ence in San Diego this past Sun­day (Feb. 2010).

Walk­er and his col­leagues Bryce A. Man­der and Sangeetha San­thanam split up a batch of 39 healthy young adults into two groups. One group napped, the oth­er did not.

At noon, both groups took a learn­ing task thought to recruit the hip­pocam­pus. The hip­pocam­pus is a region of the brain known to play an impor­tant role in the for­ma­tion of new mem­o­ries. Over the past few years, var­i­ous researchers have found that fact-based mem­o­ries are tem­porar­i­ly stored in the hip­pocam­pus before oth­er regions of the brain can oper­ate on the con­tent, espe­cial­ly the regions of the brain respon­si­ble for high­er-order rea­son­ing and think­ing.  At this point in the exper­i­ment, both groups showed sim­i­lar lev­els of per­for­mance.

Then, at 2pm, the nap group took a 90-minute nap while the no-nap group stayed awake, pre­sum­ably watch­ing the nap group enjoy­ing their nap. After nap-time both groups then took more learn­ing tests. The nap­pers did bet­ter on the tasks than those who stayed awake, demon­strat­ing their high­er capac­i­ty to learn.

The researchers inter­pret these find­ings as sup­port­ing their hypoth­e­sis that a major func­tion of sleep is to clear away all the clut­ter stored in the hip­pocam­pus to make room for new infor­ma­tion. In the words of Walk­er:

It’s as though the e‑mail inbox in your hip­pocam­pus is full and, until you sleep and clear out those fact e‑mails, you’re not going to receive any more mail. It’s just going to bounce until you sleep and move it into anoth­er fold­er.”

Walk­er also likens the brain to a sponge:

Sleep is crit­i­cal for learn­ing. It’s like the brain is a sponge. Sleep wrings cer­tain key regions out so you’re able to soak up new infor­ma­tion the next day.”

Short mid-day naps may be good because they get you into a par­tic­u­lar­ly ben­e­fi­cial part of the sleep cycle. EEG stud­ies (that mea­sure the elec­tri­cal activ­i­ty of the brain) have shown that this mem­o­ry-refresh­ing process occurs dur­ing Stage 2 non-REM sleep. We actu­al­ly spend at least 50% of our sleep­ing time in this stage, sug­gest­ing an adap­tive pur­pose for this stage of sleep:

I can’t imag­ine Moth­er Nature would have us spend 50 per­cent of the night going from one sleep stage to anoth­er for no rea­son. Sleep is sophis­ti­cat­ed. It acts local­ly to give us what we need,” says Walk­er.

man drinking coffeeNow, what about that cup of tea? Was my friend in Eng­land right? His advice is usu­al­ly spot-on, but this time he may have been mis­guid­ed.  Sara Med­nick at the UC San Diego (and author of the book: Take a Nap! Change Your Life) divid­ed her sub­jects into two groups: one group received 200 mg of caf­feine and did not nap and the oth­er group just took a nap. Then both groups under­went a bat­tery of tasks, includ­ing mea­sures of typ­ing, and mea­sures of mem­o­ry recall, tap­ping into visu­al, ver­bal, and motor mem­o­ry. She found that the day nap­pers did bet­ter on all the tasks than those who popped the caf­feiene pill. “Of course, that’s bad news for Star­bucks,” says Med­nick. Med­nick also notes: “Which would you rather be: wired or smart?”

Med­nick points out that the time dur­ing the day a per­son should nap varies depend­ing on the per­son­’s age. She says that since teenagers and young adults have a slight­ly shift­ed sleep cycle, going to bed late and wak­ing up ear­ly, their ide­al nap­ping win­dow is in the after­noon, around 4p.m. The ide­al nap­ping win­dow for adults, in con­trast, is between 1 to 3 p.m., since adults usu­al­ly sleep between 11 p.m. and mid­night and wake up between and 8 am.

Walk­er and his col­leagues are also inter­est­ed in the link between age and the func­tion of sleep. They are now inves­ti­gat­ing whether the reduc­tion of sleep as we age is asso­ci­at­ed with the well-repli­cat­ed decrease in our abil­i­ty to learn as we age. As not­ed in the offi­cial UC Berke­ley Uni­ver­si­ty press release, this is fas­ci­nat­ing research and could great­ly improve our under­stand­ing of neu­rode­gen­er­a­tive con­di­tions such as Alzheimer’s dis­ease.

Sleep­ing is Good for You

The Walk­er and col­leagues study is one among a num­ber that show that sleep, more gen­er­al­ly, can be very ben­e­fi­cial for a wide range of pos­i­tive out­comes. At UC Berke­ley, both Walk­er’s research group and Alli­son Har­vey’s group at the Sleep and Psy­cho­log­i­cal Dis­or­der Lab­o­ra­to­ry have found that get­ting a good amount of sleep at night is tied to a bet­ter immune sys­tem, meta­bol­ic con­trol, mem­o­ry, learn­ing, and emo­tion­al func­tion­ing. Most of us are famil­iar with the often cit­ed find­ing that pulling an all-nighter the night before an exam can decrease the abil­i­ty to remem­ber the infor­ma­tion by rough­ly 40 per­cent, but it’s real­ly cool to see all these oth­er ben­e­fits of sleep.

women learning pianoI can relate. Some­times when I am learn­ing a new tune on my piano, I get frus­trat­ed in the moment when I think I am no longer mak­ing progress. Some­times when I try to tack­le the song the next day after a good night’s sleep, I real­ize I have learnt the whole thing the night before! In fact, research does show that peo­ple have 20 to 30 per­cent bet­ter recall of what they learned dur­ing a piano les­son if they are test­ed after a full eight hours of sleep than if they are test­ed right after the piano les­son.

There are also ben­e­fits of sleep for cre­ativ­i­ty. Mul­ti­ple threads of research sup­port this notion, and the link between sleep­ing and cre­ativ­i­ty has been not­ed by promi­nent researchers such as Jerome Singer as well as Walk­er:

This starts to sound a lot like the basis for human cre­ativ­i­ty. The fus­ing of things that don’t seem to have any con­nec­tion. That’s what sleep, par­tic­u­lar­ly dream­ing does. Like good cook­ing, when it comes to mem­o­ry, it’s not enough to chop up the ingre­di­ents and put them togeth­er. The brain needs time to let things mar­i­nate.”

Sleep­ing may even have impor­tant affects on depres­sion. Some researchers now believe that chron­ic sleep depri­va­tion may lead to depres­sion, rather than depres­sion caus­ing one to sleep less (which was what researchers used to think was the causal link).  In one study, which I believe is still ongo­ing, Har­vey’s research group along with the Kaier Per­ma­nente Cen­ter for Health Research in Ore­gon recruit­ed 60 mid­dle and high school stu­dents to inves­ti­gate whether more sleep can low­er the risk fac­tor for depres­sion. In their study, the teens will report on their sleep habits for 12-weeks, under­go­ing 12 one-hour, once-a-week ses­sions of cog­ni­tive behav­ior ther­a­py that will focus on sleep and mood pat­terns.

It’s clear then that sleep is adap­tive for many pos­i­tive out­comes.

We are get­ting close to under­stand­ing some of the func­tions of sleep, yet soci­ety still treats sleep like a lux­u­ry. We say, ‘When I have two weeks’ vaca­tion I’m going to allow myself to sleep eight hours.’ But we would nev­er say that about water or food. If there’s some­thing that gets short­changed, it’s always sleep,” notes Walk­er.

In fact, it turns out that peo­ple who take reg­u­lar naps and get a good night’s sleep may have the abil­i­ty to learn twice as much as those who just get a good night’s rest. This is all impor­tant research, espe­cial­ly in light of the fact that about 40% of Amer­i­cans get less than 7 hours of shut-eye a night (teenagers are advised to sleep about 9 hours a night) and two-thirds of women report hav­ing dif­fi­cul­ty falling asleep more than three nights a week. As Med­nick notes: “We are a sleep-deprived nation.” Med­nick and oth­er offi­cials at UC San Diego even orga­nized a “nap-in” last year dur­ing Inter­na­tion­al Nap­ping Day (don’t you wish every day was Inter­na­tion­al Nap­ping Day?).

So, to all the nap­ping haters out there, check out the research. But real­ly, does­n’t this research all real­ly just con­firm what moth­ers have been telling us all along? Walk­er thinks so: “My research is not rev­o­lu­tion­ary, because your moth­er knew it all along.

—-  Scott Bar­ry Kauf­man, Ph.D. is a cog­ni­tive psy­chol­o­gist and writer based in New York City. His lat­est Sharp­Brains arti­cles are:

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4 Responses

  1. Mike says:

    Even dur­ing the height of the Sec­ond World War Win­ston Churchill would nap. As I recall, sev­er­al pres­i­dents were also known to nap, includ­ing Lin­coln and FDR. Per­son­al­ly, I like the idea but just do not think my employ­er would under­stand.

    Inter­est­ing arti­cle.

  2. dr. dement would be proud...almost says:

    william c. dement is a pio­neer of sleep research, and also quite a char­ac­ter who encour­ages sleep­ing dur­ing lec­tures in his stan­ford course, “sleep and dreams”. he’d be hap­py that you’re spread­ing knowl­edge about the ben­e­fits of sleep, and would wish me to remind you that DROWSINESS IS RED ALERT — a pop­u­lar phrase of his mean­ing that a dri­ver should pull over at the first sign of drowsi­ness.

    i can’t speak for dr. dement, but i’m dis­ap­point­ed by the qual­i­ty of the arti­cle.

    this is an arti­cle for a “brain fit­ness” site, so don’t you think you could have found some smart per­son to do a lit­tle edit­ing? how can a ph.d still con­fuse ‘affect’ with ‘effect’? a study which *you believe* is still ongo­ing? at “kaier per­ma­nente”? take a nap, bud­dy. here’s hop­ing the next one’s bet­ter!

  3. previous comment says:

    this is an arti­cle for a “brain fit­ness” site, so don’t you think you could have found some smart per­son to do a lit­tle edit­ing? how can a ph.d still con­fuse ‘affect’ with ‘effect’? a study which *you believe* is still ongo­ing? at “kaier per­ma­nente”? take a nap, bud­dy. here’s hop­ing the next one’s bet­ter!

    you are wrong, because if he sub­sti­tut­ed the word affect with the word effect, then the cause would be from sleep depri­va­tion. Author clear­ly stat­ed may manip­u­late, the cause of depres­sion is many. So using affect is right, because it may help rem­e­dy the state of mood.

    very well writ­ten arti­cle, do con­tin­ue author, since this day and time, we need more insight to gain more insight.

    best regards

  4. Lenny says:

    I now have an excuse for my boss when he catch­es my nap­ping on the job.

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