Thursday, February 25, 2010

Snooze and learn

In China I saw lots of schools with kids strewn across floors, fast asleep in the early afternoon. It’s a long tradition in China and has more than a touch of ancient wisdom. Science is now showing that a nap after lunch has a positive impact on memory, and therefore learning.

Sleepers learn better

Mathew Walker of the University of California, divided 39 students into two groups; both took a learning task at noon, one group slept for 90 mins at 2pm, the other stayed awake. Both took an assessment at 6pm.

The ‘sleepers’ not only did better than the non-sleepers, they performed better than they did in the first test. If the nap includes REM sleep, a clearing of the memory pathways seems to happen, "It's as though the email inbox in your hippocampus is full and, until you sleep and clear out those fact emails, you're not going to receive any more mail. It's just going to bounce until you sleep and move it into another folder." In other words, short-term memory is clear during REM, which prevents interference with long term consolidation. An intriguing hypothesis is that our memories may get worse as we get older simply because we sleep less. Walker is now investigating this hypothesis. Interestingly, staying up all night seems to reduce memory capability, and therefore learning, by up to 40%. Cramming can therefore be counterproductive.

Sleep inhibitors

Bed sharing with siblings, reading, radio, computer games, TVs and mobile phones may keep children up, limiting recovery time while sleeping, also affecting memory and learning.

Mary Carskadon, the queen of sleep research in teenagers, cites several advantages for teens to get the sleep they need:

  • less likelihood of experiencing depressed moods;
  • reduced likelihood for tardiness;
  • reduced absenteeism;
  • better grades;
  • reduced risk of fall asleep car crashes; and
  • reduced risk of metabolic and nutritional deficits associated with insufficient sleep, including obesity.

In a 1998 survey of more than 3,000 high-school students, for example, psychologists Wolfson and Carskadon found that students who reported that they were getting C's, D's and F's in school obtained about 25 minutes less sleep and went to bed about 40 minutes later than students who reported they were getting A's and B's.

Teenagers actually need more sleep than adults and late nights and early schools starts may be harming their learning and general health. Starting around the beginning of puberty and continuing into their early 20s, Carskadon and colleagues have shown, adolescents need about 9.2 hours of sleep each night, compared with the 7.5 to 8 hours that adults need. "Almost all teenagers, as they reach puberty, become walking zombies because they are getting far too little sleep," comments Cornell University psychologist James B. Maas, PhD, one of the nation's leading sleep experts. This research actually led to action with Lofgren's "Zzzzz's to A's" bill, first introduced in the U.S. House of Representatives.


The upsycho said...

As far as I can tell, children in early years education in the US have a sleep after lunch.

In South Africa, children who attend day nurseries also have a sleep after lunch. Once they go to 'proper' school, in the year they turn 7 (far more civilised age than 4!), the school day finishes at lunch time anyway!

When we first moved to the UK, our (then) 5 year old was appalled that he had to go back to the classroom after lunch.

In recent years, I have become quite prone to insomnia. Partly it's to do with being 'of a certain age', I guess, but stress levels don't help. I have certainly found that I am far less organised when I am not sleeping well, even - for want of a better word - 'thicker'. Things that would be no problem at all normally cause me brain strain when I'm sleep deprived. In fact, I am willing to bet that if my intelligence were to be tested when I have been sleeping well and again when I am sleep deprived, there would be such a discrepancy between the results, it would be difficult to believe that they come from the same person.

Catherine said...

I can remember having a post-lunch nap at my state primary school in the early 60s. All the infants (4-7) went into the hall and lay down on little camp beds after we can in from post-food playtime. I don't know how long the nap was (I was only little!), but I do know that the headteacher was regarded as being a bit 'odd' in some of her approaches to managing her school. There were many other things that I took as normal and found were anything but when we moved when I was 10. That primary school did have a better than average 11+ pass rate though.....maybe Mrs Cooper knew far more about how to give opportunities to the children in her care 50 years ago than any educational theorists since?

Mark Frank said...

The Carskadon study and other similar studies offer fairly convincing evidence of a correlation between lack of sleep and lower academic performance. But they are cross-sectional studies not longitudinal (they take a snapshot in time) so it is very hard to establish causality. There are too many confounders.

To quote this 2006 report from the Institute of Medicine.

An association between short sleep duration and lower academic performance has been demonstrated (Wolfson and Carskadon, 1998; Drake et al., 2003; Shin et al., 2003), but the question of causality has not been resolved by longitudinal studies. A 3-year study of 2,200 middle school students did not find that sleep loss resulted in lower academic performance. It only found a cross-sectional association at the beginning of the study. However, by the end of the study, as sleep time worsened, grades did not proportionately decrease (Fredriksen et al., 2004). A study of the Minneapolis School District, which delayed start times for its high schools by almost 1.5 hours (from 7:15 a.m. to 8:40 a.m.), found significant improvements in sleep time, attendance, and fewer symptoms of depressed mood (Wahlstrom et al., 2001). Further, there was a trend toward better grades, but not of statistical significance. The study compared grades over the 3 years prior to the change with grades 3 years afterwards.

Rob Alton said...

Some good points there. Ever had the 14.45 slump after eating a bread and fat based meeting/conference lunch?

The trick is getting that nap in, but not making it too long otherwise you just feel dreadful on waking.

We could learn from the Spanish here - up to 30 mins means you benefit, but more means you'll be sluggish.

I did some time in China working for a large bank. After lunch we were given keys to rooms in the training centre so we'd have a 30 minute nap.

They do start a hell of lot earlier than us though.

Cody said...

Oh sleep! All through school they teach you to not cram, and go to sleep. I fell victim to cramming in college, and I did fine. As I look back, I should have studied over time and slept before test because I definitely lost information throughout the test. I would like to know if it works the same in the real world. For example, they tell some creative designers to work for 2 days straight. Will sleep help them be more creative?