Sleep SVG (lat. somnus) – a natural physiological condition characterized by a reduced response to the world around, inherent in mammals, birds, fish and some other animals, including insects.
In addition, the word “sleep” is used to refer to a sequence of images (formed during the so-called “fast sleep” phase) that a person may remember.
Physiologically, ordinary sleep differs from other similar conditions, such as anabiosis (hibernation in animals), hypnotic sleep, coma, fainting, lethargic sleep.
Physiology of Sleep SVG
In a dream the level of anabolic processes increases and catabolism decreases.
A person’s sleep normally occurs cyclically, approximately every 24 hours. These cycles are called circadian rhythms. They are redefined every day, the most important synchronizing factor is the level of light. The level of concentration of special photo-dependent proteins depends on the natural light cycle. Among other possible synchronizing factors one should note the solar-daily variations of the geomagnetic field reaching relatively large values at middle latitudes and the daily variations of the electric field of the Earth’s atmosphere. However, the mechanism of influence of these factors on the circadian rhythm of a living organism is not yet sufficiently studied, although it is known, for example, that geomagnetic storms break the circadian rhythm as well as a sharp change of time zones – in case of geomagnetic storms the production of melatonin, a hormone regulating the circadian rhythm, decreases.
In addition to night sleep, in some cultures there is a physiologically conditioned short day’s sleep – siesta.
Immediately before bedtime, there is a state of drowsiness, a decrease in brain activity, characterized by:
- A decrease in the level of consciousness;
- Decreased sensitivity of sensory systems;
- Reduced heart rate, decreased secretory activity of the glands (salivary → dry mouth; tear → burning eyes, eyelid sticking).
Professor Richard R. Budzin has studied sleep disorders for many years at the Sleep Research Laboratory and recommends a method of rapid sleep based on six stages. In his annual report on clinical psychology, he described the various psychological approaches that were used to treat insomnia. Such treatment had previously been called stimulation control treatment. Tips include going to bed only when you want to sleep, using the bed only for sleeping, not lying in bed for more than 10 minutes if you can’t sleep – to make the bed associated only with a quick fall asleep, waking up in the morning on the alarm clock at the same time, not sleeping in the daytime.
Sleep SVG structure
Sleep – a special state of consciousness of man and animals, which includes a number of stages that are naturally repeated during the night (with a normal daily schedule). The appearance of these stages is conditioned by the activity of different brain structures.
A healthy person’s sleep begins with the first stage of slow sleep (Non-REM-sleep), which lasts 5-10 minutes. Then comes the 2nd stage, which lasts about 20 minutes. Another 30-45 minutes fall on the period of the 3rd and 4th stages. After that, the sleeper returns to the 2nd stage of slow sleep again, after which the first episode of fast sleep occurs, which has a short duration of about 5 minutes. The whole sequence is called a cycle. The first cycle has a duration of 90-100 minutes. The cycles then repeat themselves, reducing the proportion of slow sleep and gradually increasing the proportion of fast sleep (REM sleep), the last episode of which in some cases may reach 1 hour. On average, five complete cycles are observed in a healthy sleep. The sequence of stages change and their duration are conveniently represented in the form of hypnogram, which visually reflects the patient’s sleep structure.