What Happens During Sleep?

A good night’s sleep can make you feel ready to take on the day. However, bad sleeping habits can have serious health consequences. Getting the right amount of sleep is one of the best things you can do for your mental and physical wellbeing, along with regular exercise, a healthy diet and not smoking.

During sleep, your body and brain are surprisingly active. But the first assumption that when you close your eyes, you’re essentially turning off and taking a break no longer holds up to scientific scrutiny. In fact, as you fall into a deep sleep, the brain begins a series of changes that affect nearly every cell in your body.

It’s not entirely clear what exactly happens during sleep, but we know that different parts of the brain are involved in each phase of the cycle. Generally, sleep includes periods of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. During NREM, your heart rate, blood pressure and metabolism slow down.

REM sleep, on the other hand, is associated with memory formation and processing, emotional responses and imagination. It’s also linked with creativity and problem-solving skills, while being a key factor in keeping the immune system strong, which is why research suggests that people who get enough high-quality sleep are less likely to become sick or develop chronic inflammation.

In the past, scientists have used EEG recordings to determine that sleep is a distinct state from waking. Using the criteria of reversibility, recurrence and spontaneity, scientists have identified specific brain activity patterns during each stage of sleep. These have been defined as the three main phases of sleep:

There are many theories about why we need sleep. Some suggest that sleep enables us to save energy for the daytime, while others point out that it’s an evolutionary mechanism designed to protect the brain from damage and improve our ability to learn and retain information.

Some researchers have also found that sleep can improve our social and emotional intelligence. In a study published in 2022, scientists found that people who had higher quality and duration of sleep were more able to recognise other people’s emotions and expressions.

The most widely accepted theory is that sleep provides restorative functions, such as tissue growth and repair, which explains why so much of our time is spent in bed. Other studies have also shown that adequate sleep reduces the risk of certain diseases, helps to lower your cholesterol levels and can increase the effectiveness of vaccines.

It’s important to maintain a regular sleep schedule and try to relax before bed. If you’re struggling to get a good night’s sleep, see your GP. They can talk to you about some non-medical treatment options, such as relaxation training. They can also help you find an appropriate bedtime routine and set up a comfortable environment to assist with your restful sleep. If you’re experiencing persistent sleep problems, seek a second opinion from a specialist sleep doctor.