Five things you probably didn’t know about sleep

During REM sleep the concentration of neurotransmitter acetylcholine is twice what it would be when awake. This promotes the altering of connections between neurones, facilitating new links between disparate pieces of information. The Beatles classicYesterdayandFrankensteinare said to be products of sleep.

The idea that dreams only occur in REM sleepsimply isn’t true. We actually have dreams throughout all stages of sleep and even when we’re awake, as daydreams. However, it is fair to say that dreams are more common in REM than non-REM sleep as well as being more vivid, emotional, and bizarre.

Sleep deprivation leads to a sort of semi-euphoric state and has been used to treat depression since the early 1970s. Unfortunately, low mood often returns as soon as the patients are allowed to get some sleep. It also has to be used with caution as a treatment – prolonged sleep deprivation leads to impaired working memory and other health problems.

Measures of alertness by testing reaction times have shown big differences in how much sleep we need. In research carried out at the University of Pennsylvania, eight hours did the trick for most people, helping them to maintain their reaction times. But an estimated 5 per cent of the population, including, famously Margaret Thatcher, can get away with five hours or fewer.

Early to bed, early to rise doesn’t suit everyone – research has shown that some people are genetically predisposed to stay up later at night and get up later in the morning. For roughly 40 per cent of us, this is the optimum pattern, and we will feel better and be more productive if we stop trying to force ourselves out of bed at 6am.