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The Importance of Sleep on...well...Everything!

Everyone knows that sleep is important and we are all aware that a lack of sleep can lead to us feeling tired or grouchy during the day. But fewer people are aware of just how vital sleep is for our physical wellbeing and how it affects nearly every hormonal process our body undergoes. This means that when we experience sleep loss, everyday functions of our brain and body are negatively impacted, leading to all sorts of problems if this continues over time, some of which are potentially life-threatening. So what exactly are the effects of sleep on our mental and physical health?

  • Memory and cognition

Adequate sleep is vital for a wide range of cognitive tasks, with one of the most important ones being the ability to consolidate our memories. This doesn't just include the memories of our personal experiences, but also of any factual information we have learnt and our ability to improve unconscious skills such as learning to play an instrument or sport. During sleep, the information we have learnt during the day is consolidated, which means it is strengthened and ingrained into our long-term memory. If you're studying for exams, a good tip to help remember all the information is to have a nap between revision sessions. There is scientific evidence to support the use of nap breaks and a good night's sleep on memory strength and exam performance. Another important effect of sleep on our cognition is on our ability to concentrate. If you haven't had enough sleep, this can lead to a decreased ability to think, focus, make decisions and pay attention. This can become dangerous if you are a driver, as studies have shown that 30% of road accidents are due to sleepiness and that sleep deprivation has a similar effect on driving as drinking alcohol.

  • Diet, weight and diabetes

This may be surprising for some to learn that poor sleep can actually lead to a change in the kinds of food you crave and your overall weight. The hormones that are responsible for your appetite and energy usage are regulated by sleep, namely leptin (which makes you feel full) and ghrelin (which makes you feel hungry). If you aren't getting enough sleep, the hormone levels for ghrelin increases, making our appetite increase, especially for calorie-rich foods. A lack of sleep, particularly in children and teenagers, is also a predictor of obesity in later life. Insulin, the hormone which controls your blood sugar level, is another hormone that is regulated by sleep. Sleep loss affects the effectiveness of insulin, leading to higher than normal levels of blood sugar, in turn increasing the risk of developing diabetes.

  • Immune system

Sleep has even been shown to have an effect on the strength of our immune systems. When faced with a pathogen, infection or virus, our body's immune system goes into overtime to create antibodies to destroy it, keeping us safe and healthy. This vital process requires adequate sleep to work properly and suffers as a result of sleep loss. One study actually monitored people's sleeping patterns for 2 weeks before delivering a virus. Results showed that people who slept less than 7 hours were 3 times more likely to develop the cold compared to those who averaged at 8 hours or more, showing just how important sleep is for our immunity.

  • Heart health

Not only does our brain need rest, but so does our heart. When someone experiences sleep loss or disrupted sleep, cardiac functioning is put under higher stress, affecting the way the heart works in potentially dangerous ways. This is especially the case for people who have a sleep disorder, such as insomnia, or those who do night shift work, whose sleep-wake cycle is disrupted. In fact, night shift workers are twice as likely to suffer from abnormal heart rates, explaining why they experience higher rates of heart disease.

  • Mood, well-being and mental illness

And last but certainly not least is the effect that sleep loss has on our mental and emotional wellbeing. Perhaps unsurprisingly, sleep deprivation is associated with a greatly increased risk of mental health problems, with over a quarter of this population suffering from insomnia. Especially in children and teenagers, sleep loss can make them feel angry, impulsive, lose motivation and experience mood swings, making it more difficult for them to control their emotions. For many mental disorders, including depression, anxiety, PTSD and bipolar, sleep disturbance is actually one of their core symptoms, as well as a predictor of it.

Although we're resting when we fall asleep, the act itself is crucially important for a huge number of functions. Everything from our mental wellbeing to our hormone levels to our physical health relies on getting enough sleep. And when we don't, the consequences of it can be severe. So make sure you are finding the time to get the amount of sleep your brain and body needs.

If you are struggling with sleep for whatever reason and feel like it is starting to affect your mental health, get in contact with Dr Liliya Korallo at or visit her website via

Dr Korallo is a psychologist in central London who has been working with clients throughout the pandemic, helping them to manage whatever mental health difficulty or disorder they may present with. She can work in person in her office by Liverpool Street, London, or online if preferable.

By Andrew Theophani

Assistant Psychologist

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