Is the purpose of sleep to forget?

Sleep is something we all do every night (hopefully!). In fact, a third of our lives are spent asleep, but what is sleep’s purpose?

Common answers to this question reckon sleep is a way to save energy, or that sleep provides an opportunity to clear away the brain’s cellular waste. Others have stated that sleep simply forces animals to lie still, letting them hide from predators.

However, the latest concept that's come to light on why we slumber suggests we sleep to forget – not everything, of course, but just some of the things we've learnt that day.

The key to 'forgetting' seems to be in our synapses. These are the parts in between our brain cells where information passes from one cell to the next, and they form a network across the brain. Each time we learn (or remember) something, we are using these synapses. Ever heard the phrase, 'cells that fire together, wire together'? Well, that's pretty much referring to the way our synapses connect the cells in our brain to one another in a giant network.

Recent studies on mice suggest that the size and quantity of the synapses decreases as a result of sleep. Some clever scientists did some sleuthing to find one particular protein (Homer1A, if you're curious!), which is released as we sleep and starts to 'prune' or cut back on some of these synapses involved in creating memories.

Don't panic though! They also found that sleeping won't cause us to lose all of our memories. The important memories appeared to be untouched, or hardwired in the synapses somehow, so that these were not affected by the overnight weeding. 

So, why would we need to 'forget' things? Not everything we experience throughout the day needs to be remembered, especially if it's something like your friend jumping out from behind a bush to scare you as a joke. If you held on to that memory, you might be nervous about every bush you pass thinking you'll be scared again... which obviously isn't going to be the case! We need to clear out some of the old, to allow some room for the new experiences.

Go ahead, get a good night's sleep and let Homer1A give your brain a spring clean!