Your body works miracles when you sleep, and there's a good reason why we innately spend 25 years of accumulated hours dozing off.
Sleep is universal. Everyone – even animals – sleeps one way or another. It plays a crucial role in human physical and mental health: repairing tissues, forming cells, creating new pathways for the brain to remember things – something which you are not capable to do when awake.
Like food, sleep is vital to survival. Lack of sleep alters activity in parts of the brain, making it difficult for one to control their emotions in the face of change. There’s a reason why you feel slower, grumpier or even sadder during the days when you lose sleep. Worse; this may lead to chronic illnesses, depression and obesity.
Those factors alone prove the importance of sleep in our daily lives. While scientists cannot fully explain why sleep exists and why we do it, they have pointed out the benefits whenever we succumb to a much-essential slumber. But what really happens when we sleep? How does the body heal itself when the lights turn off?
According to Independent UK, sleep happens in two broad stages: the NREM, or the non-rapid eye movement, and the REM, or the rapid eye movement. NREM sleep, the light-to-deep sleep, is where the mind form memories and associates them with words and visuals. A great chunk of sleep occurs in NREM, which is divided into four stages.
Stage 1, commonly known as light sleep, is where you feel drowse. It happens quickly, usually from one to seven minutes. During this time, your muscle activity slows down, your eyes begin to droop. While your brain is still active, you can be considered as half-asleep. Small noises and movements can easily wake you up; however, you may feel muscle contractions – also called hypnic jerks – and a strange feeling of falling when you rouse from your light sleep.
Stage 2 takes up a longer part of your sleep time – about 50% during progressive cycles. It occurs within 10-25 minutes. While under stage 2, your eye movements pause, brain waves fluctuate, and there will be sudden occurrence of sleep spindles – also called rapid wave bursts. You can still be awakened easily during this stage, and just like stage 1, you will feel muscle jerks during the untimely rousing.
Stage 3 is where you slowly progress to deep sleep. It is 20 to 40 minutes in the cycle. Here, sleep spindles stop; slower, steadier brain waves called delta waves starts appearing. It would be difficult for you to wake up during this stage.
Stage 4 is when you finally arrive in your deepest sleep. The tension in your muscles calm down, you breathe slowly in a rhythmic fashion, and there is no eye movement. Ever wondered why people snore? They must be in their stage 4 sleep. This spans from 20 to 40 minutes.
Last but perhaps the most important of all, is the REM Stage. Here, your brain perks up and electrical activity bursts as if you are wide awake. Physically, your breathing becomes shallow, your eyes move rapidly in various directions, and your muscles become temporarily immovable.
The first REM occur 70 to 90 minutes after falling asleep. A complete cycle takes about a minimum of 90 minutes. This period increases as deep sleep decreases. When you wake up in the morning, you must have spent your time in stages 1, 2 and REM.
An important note: you physically lose your ability to regulate temperature during your REM sleep. Any changes in the environment can disrupt this stage. When this happens, your body will fail to follow the normal sleep cycle the next time you fall into slumber. You might slip directly into REM in order to catch up on this stage of sleep. How to avoid that? Sleep in a cool, comfortable state – a pair of silk pyjamas can help regulate the temperature of your body as you go through various sleeping stages.
Where do dreams occur, you ask? You dream in both your NREM and REM stages. Experts have described a difference between the two. NREM dreams are mostly conceptual, but REM dreams are more vivid and emotional. This makes REM a vital stage in sleep; it allows the brain to deal with situations and emotions you choose to ignore when awake.
As you wake up going through these sleep stages, your brain is refreshed, ready for the new day. Don’t be afraid to take time to doze off; reap the benefits of proper Zzzs in the right way.