The Importance of Sleeping Cycle and How to Improve It?

Why Is Sleep Important?

Sleep plays a vital role in good health and well-being throughout your life. The way you feel while you are awake depends in part on what happens while you are sleeping. During sleep, your body is working to support healthy brain function and maintain your physical health.

In children and teens, sleep also helps support growth and development. Getting inadequate sleep over time can raise your risk for chronic (long-term) health problems. It can also affect how well you think, react, work, learn, and get along with others. Learn how sleep affects your heart and circulatory system, metabolism, respiratory system, and immune system and how much sleep is enough.

Importance of sleep for Heart and circulatory system

When you fall asleep and enter non-REM sleep, your blood pressure and heart rate fall. During sleep, your parasympathetic nervous system controls your body, and your heart does not work as hard as it does when you are awake. During REM sleep and when waking, your sympathetic system is activated, increasing your heart rate and blood pressure to the usual levels when you are awake and relaxed. A sharp increase in blood pressure and heart rate upon waking has been linked to angina, or chest pain, and heart attacks. People who do not sleep enough or wake up often during the night may have a higher risk of:

• Coronary heart disease
• High blood pressure
• Obesity
• Stroke

Hormones and Sleep

Your body makes different hormones at different times of the day. This may be related to your sleep pattern or your circadian clock. In the morning, your body releases hormones that promote alertness, such as cortisol, which helps you wake up. Other hormones have 24-hour patterns that vary throughout your life; for example, in children, the hormones that tell the glands to release testosterone, estrogen, and progesterone are made in pulses at night, and the pulses get bigger as puberty approaches.

Metabolism and sleep: The way your body handles fat varies according to various circadian clocks, including those in the liver, fat, and muscle. For example, the circadian clocks make sure that your liver is prepared to help digest fats at appropriate times. Your body may handle fat differently if you eat at unusual times.

Studies have shown that not getting enough quality sleep can lead to:

• Higher levels of the hormones that control hunger, including leptin and ghrelin, inside your body
• Decreased ability to respond to insulin
• Increased consumption of food, especially fatty, sweet, and salty foods
• Decreased physical activity
• Metabolic syndrome

Respiratory and Immune Systems

During sleep, you breathe less often and less deeply and take in less oxygen. These changes can cause problems in people who have health problems such as asthma or chronic obstructive pulmonary disease (COPD). Asthma symptoms are usually worse during early morning sleep. Likewise, breathing problems in people who have lung diseases such as COPD can become worse during sleep.

Sleep also affects different parts of your immune system, which becomes more active at different times of day. For example, when you sleep, a particular type of immune cell works harder. That is why people who do not sleep enough may be more likely to get colds and other infections.

Why Do People Sleep?

Modern medicine’s understanding of sleep is like a partially assembled jigsaw puzzle. Experts can identify some of the pieces and have an idea of what the big picture looks like, but they haven’t figured out how everything fits together.

Your body cycles between being awake and asleep throughout each day, with certain processes only happening when you’re asleep. When you’re asleep, your body “powers down” and most body systems including your brain become less active. Some of the key things that happen while you’re asleep include:

Energy conservation and storage: During the day, cells throughout your body use stockpiled resources to keep doing their jobs. While you’re asleep, your body uses less energy. That lets those cells resupply and stock up for the next day.

Self-repair and recovery: Being less active makes it easier for your body to heal injuries and repair issues that happened while you were awake. That’s also why being sick makes you feel more tired and need more rest.

Brain maintenance: While you’re asleep, your brain reorganizes and catalogs memories and learned information. This is like a librarian sorting and shelving books at the end of the day. It makes accessing and using things you learn and remember easier and more efficient.

How Much Sleep Does Someone Need?

Sleep is variable from person to person. The way that people sleep and how much they need can vary widely. The number of hours of sleep that are good for your health can also change during your lifetime. In general, recommended sleep amounts by age are:

Age	Amount of Sleep Needed
Newborns (birth to 3 months)	Between 14 and 17 hours
Infants (4 months to 12 months)	Between 12 and 16 hours (including naptime)
Young children (ages 1 to 5)	Between 10 and 14 hours (including naptime)
School-aged children (ages 6 to 12)	9 to 12 hours
Teenagers (ages 13 to 18)	8 to 10 hours
Adults (18 and older)	7 to 9 hours

These sleep amounts apply to most people, but they aren’t universal. Some people need more sleep, and others need less. Variations in how much sleep you need may even be genetic. For example, some people can inherit the trait of being a “short sleeper” from a parent.

Personal circumstances and your health status can also affect how much sleep you need. If you’re sick or recovering from an injury or medical procedure, you may need to sleep more. If you’re pregnant, you may need more sleep during the first trimester.

If you have questions about how much sleep you need, especially if it’s different from the amount recommended for your age group, talk to a primary care provider. They can help you understand when that difference might mean there’s a medical issue that needs exploring.

Do I Have To Get All My Sleep At Once?

No, getting all of your sleep at once isn’t a hard-and-fast rule. In fact, sleep customs commonly vary by culture and time period. Historically, some cultures embraced splitting nighttime sleep into two periods. Throughout the world, many cultures still embrace the habit of napping. Many have their own word for it (like “siesta” in Spanish-speaking countries or the “inemuri,” a short workplace nap that’s practiced in Japan).

But like too much of anything, napping comes with a drawback. Napping for too long can affect sleep quality overnight. There’s also an increased risk for certain health problems. Talk to your healthcare provider if you often nap or want to try it. That can allow you to get the most benefit from naps without the drawbacks.

What Are the Stages of Sleep?

Sleeping doesn’t mean your brain is totally inactive. While you’re less aware of the world around you, you still have plenty of detectable brain activity. That brain activity has predictable patterns. Experts organized those patterns into stages. The stages fall broadly into two categories: rapid eye movement (REM) sleep and non-REM (NREM) sleep.

There are three NREM stages. When you fall asleep, you typically enter NREM stage 1 and then cycle between NREM stages 2 and 3. After that, you go into REM sleep and start dreaming. After the first REM cycle, you start a new sleep cycle and go back into stage 1 or 2, and the cycle starts over.

One cycle normally takes about 90 to 120 minutes before another begins. Most people go through four or five cycles per night (assuming they get a full eight hours of sleep).

What is Stage 1 NREM Sleep?

Stage 1 NREM sleep is the lightest stage of sleep. You enter stage 1 right after you fall asleep. This stage usually lasts only a few minutes, making up about 5% of your sleep time. After that, your sleep gets deeper, and you move into stage 2 NREM sleep.

What is Stage 2 NREM Sleep?

Stage 2 is still light sleep, but deeper than stage 1. During this stage, your brain waves slow down and have noticeable pauses between short, powerful bursts of electrical activity. Experts think those bursts are your brain organizing memories and information from the time you spent awake.

Stage 2 NREM sleep accounts for about 45% of your time asleep (the most of any stage). You’ll go through multiple rounds of stage 2 NREM sleep, and usually, each one is longer than the last. After stage 2, you move deeper into stage 3 NREM sleep, or enter REM sleep.

What is Stage 3 NREM Sleep?

The deepest stage of NREM sleep is stage 3. It makes up about 25% of your total sleep time in adults. But babies and children need more stage 3 sleep, and the older you get, the less you need.

In stage 3, your brain waves are slow but strong. Your body takes advantage of this very deep sleep stage to repair injuries and reinforce your immune system. The same bursts of brain activity that happen in stage 2 can also happen in stage 3, and brain waves specific to stage 3 help regulate those bursts.

You need stage 3 NREM sleep to wake up feeling rested. Without enough stage 3 sleep, you feel tired and drained even if you slept for a long time. That’s why your body automatically tries to get as much stage 3 sleep into your sleeping period as early as possible. After stage 3 NREM sleep, your body moves into stage 2 NREM, which is the gatekeeper of REM sleep.

Because stage 3 NREM sleep is so deep, it’s hard to wake someone up from it. If they do wake up, they’ll probably have “sleep inertia,” a state of confusion or “mental fog.” Sleep inertia lasts about 30 minutes.

You Like to Read: The Science of Lucid Dreaming: How to Control Your Dreams

What is REM Sleep?

Rapid eye movement (REM) sleep is the stage of sleep where most dreams happen. Its name comes from how your eyes move behind your eyelids while you’re dreaming. During REM sleep, your brain activity looks very similar to brain activity while you’re awake.

REM sleep makes up about 25% of your total time asleep. Your first REM cycle of a sleep period is typically the shortest, around 10 minutes. Each one that follows is longer than the last, up to an hour.

Conditions and Disorders

What are sleep disorders, and which of them are more common? Conditions that disrupt sleep or wakefulness are called sleep disorders. There are six main categories of sleep disorders:

• Central disorders of hypersomnolence (like narcolepsy).
• Circadian rhythm sleep-wake disorders (such as jet lag or shift work sleep disorder).
• Insomnia.
• Parasomnias.
• Sleep-disordered breathing (such as sleep apnea).
• Sleep-related movement disorders (like restless leg syndrome).
• Parasomnias can vary widely. Some affect NREM sleep only, while others affect REM sleep only.