Sleep and health: how does sleep quality affect the body?

Sleep involves several stages that alternate with each other throughout the night. After falling asleep, a person falls into a “slow” dreamless sleep, which includes three stages: as they occur, the body becomes increasingly relaxed and brain activity decreases. “Slow” sleep is up to 80% of the total sleep time, it is during this period of intensive recovery processes, tissue renewal, metabolic products are removed, including from the brain. Neurobiologists believe that “slow” sleep is also the period when the information learnt during the day is memorised: moving “files” from short-term storage to long-term storage.

The last stage of slow-wave sleep is followed by the phase of “REM sleep”, accompanied by rapid eyeball movement. A burst of brain activity is recorded on the electroencephalogram. It is believed that it is during this period that information is exchanged between consciousness and subconsciousness, and “insights” come. As a rule, the first phase of “fast” sleep lasts no more than five minutes, and the duration of the last phase can reach an hour.

A full-fledged sleep, providing maximum physical and mental recovery, should include five cycles of alternating slow and REM sleep – this requires a total sleep time of at least seven to eight hours. However, many socially active people today devote no more than six hours to sleep, and according to some research centres, every year there are more and more people who sleep less than five hours a night three times a week or more often.

• Early death. A Duke University study found that sleep deprivation increases the risk of death from various causes by 15 per cent, while researchers at the University of Warwick found that sleeping less than seven hours a night increases the likelihood of dying from heart disease by 1.7 times.
• Metabolic abnormalities. A study conducted by scientists from the University of Uppsala showed that even a short-term sleep deficit “turns on” genes that negatively affect metabolism, contributing to the redistribution of fat and muscle atrophy. Sleep deprivation also excites cannabioid receptors, leading to appetite stimulation and overeating;
• Cardiovascular disease: sleep deprivation reduces the levels of proteins that regulate genes responsible for vascular health. Regular sleep deprivation doubles the risk of coronary heart disease and is 55% more likely to cause heart failure;
• Alzheimer’s and Parkinson’s disease. It is during sleep that the brain’s glymphatic system is switched on, which is responsible for the removal of metabolic waste products from the brain: their accumulation is one of the reasons for the deposition of toxic proteins that damage neurons. Scientists from the University of Washington have found that even one restless night can trigger the accumulation of brain-damaging proteins in the brain.
• Memory impairment. Specialists from the University of Wisconsin have established: during sleep, connections between neurons are weakened – this is necessary for assimilation of new information. In addition, during sleep, the brain transfers the received information to the “section” of long-term memories. That is why in case of insomnia a person quickly forgets what he has already learnt and cannot remember new information.

Sleep disorders affect the work of all organs and cells: immunity is impaired, growth processes in children and tissue repair in adults are affected, social skills are impaired, the risk of cancer development is increased, etc.

Binge watching TV series. This refers to people who like to ‘stock up’ on episodes and then watch them all at once. Scientists at the University of Michigan (USA) have found that people who prefer to ‘stock up’ on episodes and then watch them all at once suffer not only from a lack of sleep, but also from poor sleep quality. Binge viewers complain that even if they manage to tear themselves away from watching and go to bed on time, thoughts about the series prevent them from falling asleep. Moreover, this effect can last for several days or even weeks after the end of viewing, negatively affecting the quality of sleep and wakefulness.

Blue light from gadgets. A study conducted at Harvard has helped establish that the blue light emitted by computers, phones, televisions, etc. penetrates the brain, disrupts the production of melatonin and ‘disrupts’ biorhythms. Therefore, it is important to stop using gadgets at least an hour before bedtime. Scientists also advise removing computers and televisions from the bedroom and not leaving phones on charge: flashing indicators also negatively affect sleep quality.

Gadget addiction. Scientists from the Institute of Psychiatry, Psychology and Neuroscience in London conducted a study involving more than 125,000 children with an average age of 14. It turned out that schoolchildren who had unlimited access to gadgets had more difficulty falling asleep, their sleep quality suffered (restless, interrupted), and they were more sleepy during the day compared to children whose parents regulated access to multimedia devices. At the same time, sleep disturbances did not depend on whether children took their phones to bed with them or not.

Alcohol and nicotine. Scientists from the University of Florida conducted a study that showed that drinking alcoholic beverages or smoking at least one cigarette less than four hours before bedtime reduces sleep duration by an average of 42 minutes. It has also been proven that people under the influence of alcohol fall asleep faster, but their sleep is more superficial and restless than when they are sober.

Spicy and heavy food. Eating foods rich in spices promotes active secretion of gastric juice, which can lead to heartburn, acid reflux into the oesophagus, and discomfort. Also, some spices, such as red pepper, raise body temperature, so the ‘self-cooling’ process that starts in the body before sleep takes more time and energy. Foods rich in protein and fat also have a negative effect on falling asleep: such foods reduce the brain’s sensitivity to the neuropeptide orexin, which plays an important role in regulating sleep. In addition, digestion slows down by half during sleep, so foods that require long ‘processing’ remain in the digestive tract much longer. As a result, sleep will be shallow and intermittent, leading to a feeling of ‘exhaustion’ after waking up.

Physical exercise. The director of the Sleep Centre at Johns Hopkins University claims that 30 minutes of aerobic exercise during the day significantly improves sleep quality. It is important not to exercise immediately before bedtime: the release of endorphins is similar to the effect of a morning shower on the body and brain, causing excitement that interferes with falling asleep. On the other hand, exercising an hour and a half before bedtime has a positive effect on the process of falling asleep: during aerobic exercise, the body temperature rises, and after 60-90 minutes, it drops, causing the person to feel sleepy. Strength training during the day also improves sleep: it helps to better ‘tune’ the biological clock, which has a positive effect on sleep quality.

Yoga is a good form of physical activity before bedtime: its benefits lie not only in physical activity, but also in its meditative effect: focusing on the present moment helps you stop worrying about problems and tune in to a good night’s sleep.

Three asanas that are useful to do before bedtime:

• From a cross-legged sitting position, raise your straight arms up and slowly lean forward so that your outstretched arms are on the floor. This exercise relieves strain on the neck and back.
• Lying on the floor, pull both knees up to your chest and hold this position, watching your breathing and slowly rocking from side to side. This exercise relieves pressure on the legs.
• Lie on your back with your arms and legs straight and your palms facing up. Breathe slowly and evenly, focusing on the sensations in your body, and relax as much as possible.

Complex carbohydrates. Scientists advise including complex carbohydrates in your dinner, such as porridge made from ‘grey’ grains: oats, buckwheat, barley, etc. — vegetable salads, pasta made from durum wheat flour, wholemeal bread. Studies show that these foods are not only easy to digest, without causing a prolonged feeling of heaviness in the stomach, but also help to increase serotonin levels. This, in turn, is converted into melatonin, enhancing the feeling of sleepiness.

Hot bath. Scientists at the University of Texas have found that if you take a bath with a water temperature of 40–42 °C an hour and a half before bedtime, you will fall asleep, on average, eight minutes faster, and the duration of the slow-wave sleep phase, during which the brain rests most, will increase. Experts attribute this effect to the fact that after a thermal procedure, the body cools down, which causes drowsiness.

Tidiness in the bedroom. Ideally, the bedroom should only contain items related to sleep: experts do not recommend using this room for sports, watching television, or even reading. It is also important to maintain order, clean up, avoid accumulating dirty items, make the bed every morning, and only straighten it before bedtime. Like changing clothes, this is a kind of ritual that helps you get ready for sleep.

A flashlight next to the bed or a dim night light: even if you have to get up at night, exposure to bright light will prevent you from falling asleep again, so it is recommended to use devices with localised or soft, diffused light.