Psychology Blog » Biological rhythms and sleep

Sleep in order to live long and prosper

Evie Bentley — Thu, 06 May 2010 10:41:32 +0000

Recently published sleep research suggests that

adolescents who cut down on sleep risk an increase in body weight, and
sleeping less than 6-8 hours a night leads to a 12% increase in the risk of dying early, and
even short periods e.g. one night of very reduced sleep can lead to resistance to the hormone insulin and potentially to developing type 2 diabetes.

These studies’ conclusions do not, however, mean that a few nights of reduced sleep will make you fat, develop type 2 diabetes or die in the near future; the message seems to be that 6-8 hours sleep a night is not just the norm, but really, really good for us !

To sleep, perchance to dream … or commit murder?

Evie Bentley — Tue, 16 Feb 2010 14:23:31 +0000

Some sleep disorders are well known – sleep-walking for example. But in very unusual cases people who sleepwalk behave in a highly unusual way, this is a very rare form of the disorder somnambulism when they commite violent acts.

In 2008 in the UK a middle aged man with a long history of sleep disorders actually killed his wife whilst they were both asleep. This tragedy happened when they were on holiday and the man in question had decided not to take his medication. He had a nighmare, thought he was struggling with assailants, but when he woke he found his wife dead. There is no reason to suspect that the couple were not happy together, and sleep disorder experts and the police accept that this unhappy case is one of temporary “insane automatism”.

Core and optional sleep

Cara Flanagan — Tue, 22 Sep 2009 12:26:57 +0000

I have been sent a query about core and optional sleep as there is some contradiction between what we said in the 1st and 2nd editions of the A2 Complete Companion. Looking around the other A2 textbooks, there seems to be a wide variety of explanations – most of which are not correct. Jim Horne proposed the concepts of core and optional sleep as a different perspective to the REM/non-REM distinction, which means that it is not possible to say the core sleep includes or doesn’t include REM sleep. Horne’s concept was that core sleep is essentially the first hours of sleep, and thus refers to mainly slow wave sleep (SWS) but includes some REM sleep. As the night progresses there is less SWS sleep and more REM sleep. Optional sleep is the sleep that occurs later in the night and which appears to be less crucial. This consists mainly of REM sleep but has some SWS/non-REM sleep.I hope that is clear! Thanks to Jo Haycock for pointing the inconsistency out to me.

Interactive Diagram of The Brain

Adrian Frost — Wed, 08 Jul 2009 06:26:05 +0000

Very nice little interactive diagram to be found here. You click on an activity such as ‘speech’ or ‘memory’ and the diagram indicates which part of the brain governs such activity.

Anthropomorphosis

Adrian Frost — Wed, 29 Apr 2009 22:13:16 +0000

I love the word ‘anthropomorphosis’…. it sounds like something that should happen to you in a fifties alien invasion B-Movie…. but really, of course, it means to treat something non-human as if it were human – A major danger for psychologists who pursue animal research. We must take care when we extrapolate research findings from animals to humans (‘extrapolate‘ – another lovely term) to ensure that we recognise differences between species.

But then again, let’s take flies for example, as one researcher points out:

“Flies do most things that humans do—they eat, they sleep, they fight, they mate, they forage for food”

Furthermore, as this article seems to indicate, flies can’t sleep if they drink too much coffee and find the whole business of trying to attract members of the opposite sex exhausting.

So maybe they’re not so different after all….

Sleeping keeps you out of trouble

Cara Flanagan — Fri, 11 Apr 2008 16:17:30 +0000

This is the conclusion reached by leading sleep researcher, Jerry Siegel, after decades of sleep research. In a recent article in the New Scientitst Siegel claims that the effects of sleep deprivation are actually quite small and certainly not enough to offset the potential danger of being asleep (watch out that lion is going to get you!). Evidence from the animal kingdom is surfacing all the time which increases our understanding of sleep. It appears that fur seals, like dolphins, sleep one hemisphere at a time when hunting at sea and experience no REM activity, but once back on land they revert to the more normal sleep patterns of other animals (i.e. both REM and NREM activity and whole brain sleep).Siegel suggests that the purpose of REM sleep may be just to keep the brain stem active. If an animal is sleeping one hemisphere at a time then the brain stem is constantly active. So the purpose of REM sleep is simply to permit periods of NREM sleep. This understanding brings us one step closer to understanding the purpose of sleep. But then we have to ask – why NREM sleep? Siegel agrees that NREM sleep may aid some biological processes (e.g. production of neurotransmitters) but again doubts that it performs any vital functions that can’t be achieved during relaxed wakefulness. If it was vital how can we explain the fact that bullfrogs never sleep and that dolphins perform as well on vigilance tasks after 5 days sleep deprivation.Increasing knowledge of the sleep patterns of different animals suggests that it is ecology rather than biology which explains sleep. Currently only 150 mammals out of a total of 5000+ have been studied and other animal groups have been studied even less. Siegel argues that, on the basis of the current knowledge, the only factor that explains all sleep patterns is that species sleep for as long as they can get away with. The little brown bat sleeps a massive 20 hours per day which shouldn’t happen if sleep was related to size, metabolic rate or danger. The one factor that explains its amount of sleep is the fact that the brown bat eats flies that comes out for a few hours each night. In other words, the bat sleeps because it can and can still survive. Siegel points out that animals are actually safer when asleep; being awake is riskier because you may get injured and may be noticed.Hmmm. But all of this doesn’t explain why I feel so rough after a bad night’s sleep.