It is rather a wonderful phenomenon that during sleep our body performs numerous activities to maintain homeostasis as well as doesn’t interrupt our sleep. Most dictionaries define sleep as a state or condition of mind and body wherein the nervous system is practically inactive, muscles are relaxed, and the eyes are closed and consciousness is partially or completely suspended..
It is an interesting aspect to know about sleep and the stages involved in it. Do you wonder that our body does so much even when our consciousness is almost suspended? So basically our sleep can be divided into stages and broadly it is classified as REM (Rapid Eye Movement) and NREM (non-REM) sleep. NREM is further classified as stages 1, 2, 3, 4. These stages are of great significance as there are variations observed in each of the stages of sleep.
What happens in each of the stages?
It is very important while purchasing HGH products for body management, you should be aware of the higher levels during sleep that is required in different stages.
- Stage 1 – The first stage of sleep is stage 1 wherein the eyes are closed yet they move slowly and also muscle activity is slowed down. Have you ever felt like falling during sleep? If yes (actually everyone will experience this at least once), then this is the time or stage when you feel so. This is better known as hypnagogic hallucination. Also you can easily be awakened.
- Stage 2 – Here, the heart beat slows down and also the body temperature is lowered. This stage lasts for not more than 20 minutes.
- Stage 3 – This stage lies in between the phase of light sleep and very deep sleep and hence is a transitional stage of the sleep stages.
- Stage 4 – In this stage, deep sleep is experienced. This stage lasts for about 30 minutes.
- REM (Rapid Eye Movement) – This is the last stage of sleep. In this stage, respiration and brain activity is increased, blood pressure rises, muscles are temporarily paralyzed and also eye movement is observed. Most dreams occur in this stage. After REM is over, we go back to stage 2 of sleep.
Have you noticed that sometimes we remember our dream while at other times we simply forget? The answer to this question lies in realms of the stages of our sleep. Since we dream during REM (we get floating images in NREM), so if we wake up right after REM then we remember our dreams. If we move to stage 2 after REM and then wake up, we won’t be able to recall our dream. Thus, remembering dreams is subject to the time when we regain consciousness. Moreover, we dream more than once during our sleep.
Physiological changes in sleep
The physiological processes of our body vary in the different stages of sleep. The breathing during NREM is regular while during REM is irregular. Another parameter that varies is the arterial blood gases. The pCO2 has higher levels during sleep (both stages) and pO2 and SaO2 are low than in conscious state. There are several other parameters like pulmonary arterial pressure and intercostals muscle activity is also altered during the stages of sleep.