Lack of sleep and how it affects the brain


During deep sleep the brain is working hard. One of the main things the brain is doing is moving memories from short-term storage into long-term storage, allowing more short-term memory space for the next day. If you don’t get adequate deep sleep then these memories will be lost. You might think: I’ll cut back during the week and then make up for it at the weekend, but it doesn’t work like that because memories need to be consolidated within twenty four hours of being formed.

Therefore if you are revising or taking an exam you should make sure that you get a good night’s sleep. In one study, people who failed to do so did 40% worse than their contemporaries.

Rapid Eye Movement

REM sleep is the phase when you are usually paralysed, but the eye muscles are not paralysed, and that’s why it’s called rapid eye movement (REM) sleep.

During REM sleep one of the stress-related chemicals in the brain, noradrenalin, is switched off. It is the only time of day that this happens. It allows us to remain calm while our brains reprocess all the experiences of the day helping us come to terms with particularly emotional events.

We get more REM sleep in the last half of the night, which means that if you are woken unexpectedly the brain may not have dealt with all your emotions which could leave you stressed and anxious. Drinking alcohol late at night is not a good idea as it reduces your REM sleep while it’s being processed in your body.

Lack of sleep

In an experiment at the University of Surrey’s Sleep Research Centre, the volunteers were randomly allocated to two groups. One group was asked to sleep for six-and-a-half hours a night, the other got seven-and-a-half hours. After a week the researchers took blood tests and the volunteers were asked to switch sleep patterns. The group that had been sleeping six-and-a-half hours got an extra hour, the other group slept an hour less.

Computer tests revealed that most of them struggled with mental agility tasks when they had less sleep, but the most interesting results came from the blood tests.

What they discovered is that when the volunteers cut back from 7 1/2 to 6 1/2 hours’ sleep a night, genes that are associated with processes like inflammation, immune response and response to stress became more active. The team also saw increases in the activity of genes associated with diabetes and risk of cancer. The reverse happened when the volunteers added an hour of sleep.


Training hard requires adequate rest. Sleep (along with nutrition) is a major part of the post-workout recovery process. Getting enough sleep is vital, not only physiologically but psychologically as well, therefore it’s important to get a good balance between training hard and recovery. Power naps, weekend lie-ins and early nights can all help to make you fitter, healthier, happier and perform better.


How much can an extra hour’s sleep change you?

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