## Overview If you suffer from daytime sleepiness, inattentiveness, and/or bad moods at least three days a week, it is a clear sign of sleep disorders. There are two types of insomnia: a disorder of falling asleep and a disorder of sleep maintenance. The mechanism is always the same — the increased activity of certain brain systems that cause a person to be unable to relax. Episodic insomnia lasts no more than a week and is associated with some kind of emotional experience. If the sleep disorder has lingered and the quality of life suffers, it is time to see a doctor. It is important to catch it early, as insomnia quickly turns into a chronic disease. ## What decreases sleep quality? __Sensory overload.__ This ===can occur due to overwork, as the nervous system is toned down and while you sleep you continue to solve issues accumulated during the day. __Overeating or increased physical activity.__ This is familiar to those who work late and then go to the gym, eat a heavy dinner and fall into bed. He or she seems to sleep, but the sleep is discontinuous and fragmented. __Excessive drinking.__ Alcohol allows you to fall asleep quickly and sleep for a long time, but upon awakening, a state of brokenness persists, because the sleep was shallow. When the processing of alcohol in the liver ends, the body awakens before it has had time to rest. __Sensory stimulation.__ Spending the evening browsing social networks on smartphones and tablets, neon lights and street lights outside the window, and lights in the house all impair the synthesis of the hormone of darkness, melatonin, which makes sleep shallow. __Mental state.__ Lack of exercise, stress, and anxiety lead to the person seeming to sleep for a long time and not wanting to get up. However this is shallow sleep due to overactivation of the nervous system, when it is difficult to reach the deep, relaxing stages of sleep. ## How much sleep is needed? There is an innate need for sleep, but it is individual — some people only need six hours (5 % of people), while others need nine. However, the International Society of Sleep Scientists has calculated a norm of sleep that helps the body recover, which is seven to nine hours. Regularly sleeping less than seven hours is fraught with health risks. A study was conducted when volunteers were deprived of only two hours of sleep for two weeks and their reaction rate was measured, which got worse every day. ## How do you measure sleep quality? There are many devices that allow you to monitor your sleep. This function is included in most fitness bracelets and smart watches, and there are also devices specially designed for this purpose. ## What are the indicators to strive for? __Duration:__ seven to nine hours of sleep from falling asleep to waking up. __Structure:__ The duration and sequence of sleep phases are important. Ideally, slow sleep should occupy about 75 % of all time, since it is responsible for physical recovery, some cognitive processes and episodic memory. Fast sleep accounts for the rest of the time. Its task is to restore the mental state and procedural memory. __Number of awakenings:__ A healthy person has up to ten awakenings at night, but they take 5-10 seconds and are not remembered. Longer awakenings twice a night are also possible, but not for more than 5 minutes. __Efficiency:__ Ratio of actual sleep time to time spent in bed after lights out. Normally, this ratio should be 85 % or greater.