Sleep takes up a third of our lives. Let’s find out how circadian rhythms, melatonin, and sleep phases are related to it.
What Are Circadian Rhythms and Why Do You Need to Know About Them?
Circadian rhythms are changes in our body’s biological processes throughout the day. They depend on various natural factors, the most important of which is light exposure. Circadian rhythms affect our sleep-wake cycle, metabolism, hormone production and body temperature.
An important part of circadian rhythms is the production of the hormones melatonin and cortisol. In the morning when the sun rises, your body receives a signal that daylight has begun, your body temperature rises, the hormone cortisol is released (giving you energy for the day), and the hormone melatonin production stops.
As darkness falls, your melatonin levels begin to rise so that you can rest and get a good night’s sleep until the wee hours of the morning. That’s why it’s so hard to get up in the winter when there’s still no light outside the window in the morning, and why you wake up at 5 a.m. on short summer nights. And this is just one example of how circadian rhythms work. They affect the work of the intestine (its peristalsis starts around 08:30 and decreases after 10:30 pm), the release of testosterone (maximum – at 9 am) and even the coordination of movements (the best – at 2:30 pm).
As we age, our circadian rhythms change: starting at age 30, melatonin production decreases each year, and the body naturally wakes up earlier and earlier.
When your circadian rhythms are disrupted (e.g., you prefer a constant nighttime lifestyle and prefer playing at the best online casino – 20Bet at 2 am), your body’s aging rate increases (according to a study by scientists from the Massachusetts Institute of Technology).
What Are the Phases of Sleep?
The entire human sleep process consists of several cycles, each lasting 70-120 minutes. Each cycle = going through all the stages of sleep. Sleep cycles can vary from person to person and from night to night, depending on a wide range of factors, such as age, normal sleep patterns, alcohol use, sleep disturbances.
There are two phases of sleep: slow (NREM – Non Rapid Eye Movement) and rapid (REM – Rapid Eye Movement).
Stage 1. 1-5 minutes. State of drowsiness. The body is not completely relaxed, although body and brain activity begins to slow down with periods of brief movements (twitches). At this stage, there are slight changes in brain activity associated with falling asleep.
Stage 2. 10-60 minutes. Superficial sleep. Body temperature decreases, muscles relax, breathing and heart rate slow down, eye movements stop.
Stage 3. 20-40 minutes. Deep sleep. Muscle tone, pulse and respiratory rate decrease, the body relaxes even more. It is more difficult to wake a person who is in this phase. Experts believe that this phase is crucial for the body’s recovery processes, strengthening the immune system, and increasing creativity and memory.
Rapid Eye Movement (REM – Rapid Eye Movement) is the 4th stage of sleep. 10-60 minutes.
The first time it occurs about 1.5 hours after falling asleep and can last only 5 minutes. It then repeats at the end of each cycle, becoming longer each time, especially in the second half of the night.
During REM sleep, brain activity increases, approaching wakefulness levels. At the same time, the body experiences atonia, a temporary paralysis of muscles, with the exception of the eyes and the muscles that control breathing. Even though the eyes are closed, you can see how quickly they move, which is why this stage has its name – REM – Rapid Eye Movement.
Rapid eye movement sleep is thought to be essential for effective cognitive functions such as memory, learning, and creativity. REM sleep is known for having the most vivid dreams, which is attributed to a significant increase in brain activity. Dreams can also occur during other stages of sleep, but they are most intense during REM sleep.
What are the benefits of knowing about the phases and stages of sleep?
Sleep stages are important because they allow the brain and body to recover and develop. Lack of sleep affects our memory and ability to think clearly, and sleep deprivation can lead to neurological dysfunctions such as mood swings and hallucinations. Those who do not get enough sleep are at higher risk of developing obesity and cardiovascular disease.
For a healthy sleep and rested state, you need to go through 3-6 cycles per night. And it’s easiest to always wake up in stages 1 or 2 of slow sleep. You can calculate these stages yourself or use various apps and gadgets to do so.
What’s About Daytime Sleep?
Yes, if it doesn’t last more than 20 minutes (so-called energy sleep). Otherwise, you will fall into a deep sleep – it will be difficult for you to wake up and you will feel “broken”.
If you need more time, sleep a full 90-minute sleep cycle. Less or more time will again cause you to feel sluggish upon awakening.
An alarm clock can help control waking up. Just consider the time you need for the process of falling asleep when planning your daytime sleep. If, for example, you pass out in 10 minutes, set the alarm clock 30 minutes in advance for a full 20-minute nap.