The surprising secrets of sleep

We spend almost a third of our life sleeping. In mammals the need for sleep is so intense that natural selection has found a way to always guarantee it. An example of this can be observed in dolphins, whose two cerebral hemispheres take turns to sleep during long oceanic journeys.

The question soon arises, why is sleep so important? We tend to think that when we sleep, our body and mind shut down. But this could not be further from the truth as sleep is a very active period during which a lot of processing and restoration occurs. Neurons synthesise proteins and the rest of our cells also perform a similar process to renew themselves ready for the next bout of activity.

Every day, our brain takes in an astonishing amount of information, but rather than being directly recorded, it needs to be processed and stored. Overnight, new knowledge and experiences suffer a transformation process called ‘consolidation’. Every time we remember something, we reactivate its memory and make it more stable, a similar process to when we go over the lines of a pencil drawing to pronounce it more. This reactivation occurs unconsciously during the day, but stronger, long-term memory is formed during sleep.

Other times, as if by magic, a skill we have learnt seems to improve without practising. Researchers have successfully demonstrated that a period of sleep after practising a skill will increase speed of execution of a task and reduce the number of errors.

And finally, is sleep the key to intuition and creativity? Intuition involves the spontaneous and seemingly illogical problem resolution, while creativity is symbolised by novelty and the unusual.  These two concepts have a lot in common, as they are characterised by their use of ‘hidden knowledge’ and tend to happen unconsciously. Dreams are a big promoter of these abilities that seem to happen as if by magic. However, they are based on the reprocessing of previous information that is already stored in the brain. While we sleep, this information is combined and gives way to the extraction of regularities, deductions and patterns. When we wake, we have generated what we deem to be a spontaneous discovery.