We do it for about one third of our lives, but little is known about why we sleep. However, bit by bit, research is unpicking the mysteries behind what happens when we close our eyes at night. Here, we’ll look at what we’ve learned so far about the effects sleep has on one of our most complex and vital organs – the brain.
Keeps your memory sharp
If you easily forget everyday things like where you put your keys or you find it difficult to commit new information to memory, lack of sleep may be to blame. In 2014, scientists at New York University School of Medicine and Peking University Shenzhen Graduate School discovered that new connections between brain cells, known as synapses, are formed during sleep. These new connections mean that we are learning and forming new memories. The research showed that slow-wave or deep sleep is vital for creating memories as it is during this phase that the brain is replaying activity from earlier that day. At this stage, sharp wave-ripples move learned information from the hippocampus to the neocortex, thereby creating long-term memories.
So whether you’re trying to master a new skill, such as knitting or driving, learn a new language or you just want to be able to remember what you came into a room for, more quality sleep could be just what you need.
Protects your mental wellbeing
Most of us find that our outlook on life tends to be more positive after a good night’s sleep. But you may not realise the extent to which sleep is protecting your mental wellbeing. In 2007, research by psychologist Matthew Walker of the University of California, Berkeley in collaboration with Harvard Medical School found that sleeplessness can trigger psychological disturbances. The researchers showed images to both rested and sleep deprived participants and monitored the amygdala, which is a part of the brain involved in processing emotion. In sleep-deprived subjects, they observed a 60 per cent increase in activity when shown gruesome images. They also found a breakdown in communication between the amygdala and the medial prefrontal cortex, which helps to contextualise emotions and experiences, in the participants who hadn’t slept. Instead, the amygdala communicated with the locus coeruleus, which is a part of the brain that is involved with physiological responses to stress and panic. This suggests that sleep helps us to keep our emotions under control.
There is a clear and close link between a lack of sleep and mental health problems such as anxiety and depression. Sleeplessness is also thought to trigger manic episodes in bipolar individuals. The importance of adequate shuteye when it comes to staying mentally well cannot be understated so if you’re struggling with negative or heightened emotions, you might want to try improving your sleeping habits.
You may not realise it but getting a quality night’s rest makes you a more creative thinker. Creativity involves making connections between things that are not obviously associated and seeing novel patterns in your surroundings. In a study carried out at the University of Lübeck and the University of Cologne, participants were presented with a cognitive task with a hidden abstract rule. The study showed that more subjects gained insight into that hidden rule after sleep than after wakefulness. This suggests that sleep helps us to be more insightful. Indeed, anecdotally we know that sleep can help us to solve problems and come up with ideas. For example, golfer Jack Nicklaus reportedly had a dream that helped him to improve his golf swing and Paul McCartney has spoken about waking up from a dream with the tune to The Beatles song Yesterday in his head.
Another study showed that a lack of sleep had a significant detrimental effect on divergent thinking – a method used to generate creative ideas by coming up with many possible solutions. Some subjects were deprived of sleep for 32 hours while others slept normally. The participants were then presented with figural and verbal tests that examined their ability to think flexibly and originally. Those who were sleep deprived performed significantly worse than those who had a normal night’s sleep.
So whether you want to solve a problem in your personal life or at work or you simply want to open yourself up to creative inspiration, make sure to catch your z’s at night.
Makes you a better decision maker
Perhaps unbeknownst to you, a decent night’s slumber makes you more likely to take sound decisions. Research by Washington State University showed that a lack of sleep impedes decision making in a crisis. The study recruited 26 healthy adults, 13 of whom were selected to go 62 hours without sleep. They were presented with a task in which they were shown a series of numbers that had a hidden ‘response’ or ‘non-response’ value. When the subjects correctly identified a ‘response’ number, they were rewarded with pretend money. When they made a mistake, they lost money. However, half way through the task, the contingencies were reversed. This change confused the sleep deprived group, which had almost no success even after they had been shown 40 numbers with reversed contingencies. The group that had slept, meanwhile, caught on to the change within 16 numbers.
Whether you’re taking decisions in a crisis or just making everyday judgements in your personal and professional life, a proper night’s sleep could help you to come to the right conclusions.
Need to clear your head? Well, a study by the National Institute of Neurological Disorders and Stroke suggested that sleep may actually help to clear the brain of damaging molecules associated with neurodegeneration.
Using mice, the scientists found that a plumbing system called the glymphatic system opens during sleep, letting fluid move quickly through brain. The mice were injected with a protein associated with Alzheimer’s disease. The scientists compared how long the protein lasted in their brains when they were awake and when they were asleep. They found that it disappeared more quickly when the mice were asleep. This suggests that sleep helps to flush out toxic molecules from the brain.