The Importance of Sleep » The Unclouded Path

We all know of the importance of sleep to our health. If we don’t get enough, we feel groggy, become easily frustrated, and can’t concentrate. But sleep is essential for many other vital functions that you may not be aware of. Lack of sleep impairs those functions too, and if you get too little for too long, you could be seriously harming your overall health.

How Does Sleeping Work?

There are four phases in a sleep cycle: N1, N2, N3, and REM. The N phases are non-REM sleep (NREM), and the REM phase is rapid eye movement sleep. N1 is a sort of relaxed wakefulness and is the part of sleep we associate with nodding off. N2 is a slightly deeper sleep from which it’s still easy to be awoken. N3 is known as deep sleep and is associated with forming memories. REM sleep is where most dreams occur.

A normal sleep cycle goes from N1 to N2 to N3 to N2 to REM and lasts about 80-120 minutes. You normally go through 4-6 of these cycles in a good night’s sleep. When you wake up from sleeping depends on your circadian rhythm, sleep-wake homeostasis (your “sleep debt” so to speak), environmental factors, or in many cases, your alarm clock. If you wake up without an alarm clock or some other forceful interruption, it’s most likely shortly after a REM phase or during one.

Why Do We Need Sleep?

In addition to making us feel refreshed, sleep allows the body to perform regenerative processes and the brain to recover. You can’t stress the importance of sleep enough because it’s absolutely vital. Without sleep, a person’s physical and mental health deteriorate, eventually leading to death. These are the main ways sleep helps you:

Sleep, especially deep sleep, helps the body repair itself. During deep sleep, the body converts the food you ate during the day into proteins to build tissue. Growth hormone is also produced during this time, which helps repair muscles and any other damaged tissue.
The brain recovers its stores of energy during sleep. Glycogen, a sugar compound that the brain uses for energy, increases during sleep.
It allows the brain to purge metabolic waste products. When it’s active, the brain produces toxic waste products, like reactive oxygen species (highly reactive molecules containing oxygen also known as free radicals) and various harmful proteins. During sleep, all that activity slows down and give the brain a chance to clear up the mess.
Sleeping helps the brain consolidate information. Throughout the day, you encounter a lot of information, and most of it’s useless. During sleep, the weak neural connections (synapses) shrink and are “weeded out”, while the strong ones remain. This allows the brain to maintain only the synapses that matter.
It helps learning and memory, too. Research seems to show that declarative memory (memories about facts, concepts, and experiences) gets strengthened mostly during NREM sleep, and procedural memory (memories about how to do things) gets strengthened during REM sleep. REM sleep also seems to help with declarative memory if the content is complex and emotionally charged. In addition, rest improves concentration, which helps gather the information for memories as well as retrieve it. This leads to faster response times and more fluid problem-solving. The role of sleep on learning and memory is still an active area of research, so there’s much more to discover.
Sleep helps maintain immune function. Numerous studies have shown that sleep deprivation impairs the immune system. In fact, test animals that were kept awake eventually lost all immune function and died a few weeks later.
Many hormones are regulated by the sleep-wake cycle. Some of these hormones, like ghrelin and leptin, regulate appetite. But without proper sleep, the balance of these hormones gets messed up, leading to overeating and weight gain. In addition, growth hormone (helps build tissue) and thyroid stimulating hormone (stimulates the thyroid, which regulates tissue metabolism) are affected by sleep as well. Throwing these out of balance causes all sorts of problems, like reduced wound healing and reduced insulin sensitivity respectively.
Sleep helps regulate mood. You’ve probably noticed this yourself. If you don’t get enough sleep, you get cranky and frustrated easily. Research seems to suggest that sleep helps keep the amygdala (the part of the brain that regulates emotions) working properly.

How Much Sleep Do You Need?

As a general rule of thumb, the older you get, the less sleep you need. But because of school, work, or other issues, most people don’t get enough. Here’s a breakdown of how much sleep you should be getting according to age:

0-3 months old: 14-17 hours
4-11 months old: 12-15 hours
1-2 years old: 11-14 hours
3-4 years old: 10-13 hours
5-12 years old: 9-11 hours
13-17 years old: 8-10 hours
18-64 years old: 7-9 hours
64+ years old: 7-8 hours

Things That Improve the Quality of Sleep

You might not be able to get enough sleep, but you can certainly try to improve the amount that you do get. There are a few ways that you can make sure you’re getting quality sleep:

Try to maintain a constant sleep schedule. No binge sleeping on weekends. Your circadian rhythm influences your body temperature and when you feel sleepy. While NREM sleep is relatively independent of the circadian influences, REM sleep occurs around your body temperature minimum during the cycle. Having an irregular sleep schedule means you’re going out of sync with your circadian rhythm, which could lead to poorer quality sleep overall.
Keep away from light sources, especially blue light. Light during nighttime suppresses melatonin levels, which lead to an increase in body temperature and a decrease in sleepiness. Blue light has the strongest effect, which is a problem since lots of artificial lighting has blue light. Why blue? Well it’s been hypothesized that we evolved to be sensitive to blue light because it’s the color of the sky. When night turns into morning, the color you see the most is blue.
Don’t eat or drink anything with caffeine close to bedtime. This includes coffee, tea, chocolate, and soda. Caffeine interferes with adenosine, which acts a regulator of sleepiness. Caffeine’s also a stimulant, which means that it makes you more active.
Try to keep the room temperature from getting too high. Your body temperature drops during sleep. If the temperature is too high, it will interfere with your sleep, and you might not get sleep that’s deep enough.
Don’t do anything too active right before bedtime. Plan your day so that all of the strenuous stuff happens during daytime. Being active at night makes it harder for you to fall asleep.