Why Skipping Good Night’s Sleep Is Not Good for Your Health

Sleep is a major part of everyone’s routine. Yet, many don’t realize and neglect the importance of sleep. This is concerning because lack of sleep can seriously affect physical and mental health. This article dives into why we sleep and what happens when we don't get enough sleep.

Why do we sleep?

Even though we spend about one-third of our lives sleeping, scientists have yet to decipher exactly why we need sleep.


Some may believe that sleep doesn’t have a single function; instead, it has many vital functions. These include developmental changes, energy conservation, brain waste clearance, immune system support, cognitive health, performance, psychological well-being.

By ensuring all these functions work properly, sleep helps keep the organism in optimal conditions for survival.

It's unclear how long humans can survive without sleep, but one thing is sure: you can't avoid it completely. Even if you try, your brain will eventually force you to sleep after a while.

When you frequently sleep less than needed, you accumulate sleep debt. Your body can adapt and compensate for lost sleep, but it typically takes several days to fully recover.

What happens when we sleep?

Sleep is a complicated physiological process that goes far beyond just closing your eyes and counting sheep. Your brain doesn’t shut down completely when sleeping. In reality, it remains active, coordinating essential functions to maintain your body and mind healthy.

During sleep, nearly every part of the body experiences changes, such as decreased heart rate and relaxed muscles.

Stages of sleep


Sleep is not uniform; a typical night’s sleep comprises 4 to 5 sleep cycles, each consisting of four main stages: non-rapid eye movement (NREM) sleep, subdivided into stages N1 (light sleep), N2 (deeper sleep), and N3 (slow wave sleep SWS), and REM sleep.

REM sleep got its name because your eyes move rapidly in various directions during this sleep stage, which doesn't happen during non-REM sleep.

Each stage represents the depth of sleep and shows different characteristics of brain waves, muscle tone, and movement patterns. See more details in the table below:

Type of sleepSleep stageWhat happensDuration
NREMN1This stage is a transition between wake and sleep. In N1, your brain activity slows down, and your muscles relax, but you might still experience some movements. You're relatively easy to wake up during this stage.1 to 7 minutes
NREMN2In N2, the body enters a more relaxed state. This includes a drop in temperature, relaxed muscles, and decreased heart and breathing rates. Your brain activity slows down, although short bursts of activity may still occur. This stage has been positively associated with memory consolidation.10 to 25 minutes
NREMN3N3 is the deepest sleep stage; your muscles relax more, and your heart rate and breathing slow down. N3 is also called slow wave sleep (SWS).20 to 40 minutes
REMDuring REM, your brain activity is similar to when you’re awake, but your muscles are completely relaxed, except for the ones that control essential bodily functions. This is also when your eyes move around quickly, and most of your dreams occur.10 to 60 minutes

Sleep progresses in the following order: awake, N1, N2, N3, REM. Sleep cycles can change as the night progresses; the first ones are shorter, lasting between 70 and 100 minutes. Later in the night, they can reach 90 to 120 minutes.

You spend most of your sleep time, around 75–80%, in NREM sleep and the rest in REM sleep. Also, how much time you spend in each sleep stage can change as the night goes on.

Why does sleep matter?

In humans, sleep plays a crucial role in supporting processes that contribute to mental and physical health. Here are some potential functions of sleep:

Physical health

While you sleep, your body undergoes critical processes to your physical health. During sleep, your body repairs damaged cells, tissues, and muscles, ensuring they function properly. That’s why you wake up feeling refreshed after a good night’s sleep.


Sleep is crucial for maintaining a strong immune system, regulating the release of hormones, managing inflammation, and controlling metabolism. These functions contribute significantly to overall health and well-being.

Immune function

Sleep and immunity are closely linked. When your body is infected by pathogens, it can produce inflammation, which is an energetically taxing process, that may make you feel sluggish. Therefore, sleep can help your body rest and recover.

But that’s not all. Good quality sleep can make you less susceptible to infections, improve outcomes if you get sick, and lead to a better antibody response to vaccines.

Cognitive functions

While asleep, your brain is processing information gathered throughout the day. This happens in both NREM and REM sleep.

During the NREM stages, the brain acts like a filter, deciding what memories to keep and what to discard. As sleep deepens, selected memories are strengthened.

While you’re in REM sleep, your brain is still consolidating memories. It may also process emotional information.

Getting enough quality sleep is essential for optimal cognitive performance. This is because sleep supports various cognitive abilities, including:

  • Attention. Adequate sleep is needed for sustaining attention and maintaining alertness.
  • Problem-solving and creativity. Sleep may support problem-solving abilities and boost creativity.

Metabolism and weight management

Sleep helps support metabolism in many ways. It helps regulate key hormones such as leptin and ghrelin. Leptin signals a feeling of fullness, while ghrelin stimulates appetite.

Insufficient sleep often leads to a decrease in leptin levels and an increase in ghrelin levels. This can lead to overeating and, consequently, weight gain.

Sleeping well makes you more likely to make healthier food choices and engage in physical activity, which may help keep a healthy weight.

Constantly high blood sugar is another factor that may contribute to weight gain. Adequate sleep plays a role in blood sugar regulation and supports the body's ability to use glucose effectively.

Hormone regulation and reproductive health

Sleep and your body’s internal clock influence the levels of various hormones in your body. Some of these hormones include:

  • Growth hormone. This hormone released during sleep promotes tissue growth and supports metabolism.
  • Cortisol. Levels peak in the early morning, making you feel alert.
  • Melatonin. Released when it’s dark, it helps promote sleep.
  • Sex hormones. In women, estrogen and progesterone levels may change with the menstrual cycle, pregnancy, and menopause. Fluctuations in these hormones can influence sleep quality and timing. In men, testosterone, the main sex hormone, peak in the morning, contributing to increased alertness; adequate sleep is crucial for maintaining healthy testosterone levels.

Cardiovascular health

Ensuring you get enough sleep is a fantastic way to take care of your heart. Insufficient sleep has been linked with an increased risk of obesity, type 2 diabetes, and high blood pressure. It can also influence how well you eat and how much you exercise. Combined, these factors can raise the risk of developing cardiovascular disease, such as stroke and heart attack.

Emotional well-being and mental health

Sleep and mental health go hand in hand — the quality of your sleep can affect your mental health, while your mental health can impact how well you sleep.

Scientists can’t explain the exact reasons behind this connection. However, an extensive research has been done to examine sleep's role in processing information, regulating emotions, and controlling behavior.

How much sleep do we need?

The amount of sleep someone needs can vary throughout life and from person to person. Experts recommend that adults get at least 7 hours of sleep per night as extensive research indicates that sleeping less than 7 hours is associated with various adverse health consequences.

But it's not always the same. Sleep needs can vary from person to person and can also change over time:

Age groupRecommended hours of sleep
Newborn (0–3 months)14–17 hours
Infant12–16 hours
Toddler11–14 hours
Preschool10–13 hours
School age9–12 hours
Teen8–10 hours
Adult7–9 hours

What are the consequences of sleep deprivation?

More than a third of American adults sleep less than 7 hours a night on a regular basis. This is concerning as lack of sleep has been linked to several health problems. You may feel the effects of sleep loss in both the short and long term.

Short-term effects

Not getting enough sleep can make you feel excessively tired during the day. It may also mess with your ability to focus and pay attention, making it hard to perform everyday tasks and stay productive. Plus, it can make you more moody and irritable, which may impact your personal and professional relationships.

Long-term effects

Not getting enough sleep on a regular basis, whether unintentionally or on purpose, can get you into trouble.

Research shows that getting less than 7 hours of sleep per night increases all cause mortality, although the study was limited to the East Asian population.

Insufficient sleep can increase the risk of developing several health issues, including excessive weight gain, type 2 diabetes, high blood pressure, high cholesterol, heart disease, gastrointestinal disturbances, mental health conditions like depression and anxiety, dementia, and certain types of cancer.

How to get a good night’s sleep?

If you want to sleep better at night, the first step is to try to develop healthier sleep habits. Here are some tips that might help:

  • Sleep and wake up at the same time every day.
  • Avoid heavy meals, caffeinated drinks, and alcoholic beverages before bedtime.
  • Avoid limit screen time before bed.
  • Exercise during the day and get some sunlight exposure.
  • Make sure your bedroom is dark, quiet, and cozy.

Busting top myths about sleep

Sleep is a complex topic, but scientists have helped debunk many myths and misconceptions surrounding it. Understanding what's true or not can help you improve your sleep quality.

Sleeping longer means you're more rested

Oversleeping can sometimes lead to a feeling of grogginess, known as sleep inertia. Sleep needs vary from person to person, but most people need between 7 and 9 hours to feel rested and energized.

You can catch up on lost sleep over the weekend

While you may feel temporarily more rested after sleeping in on weekends, it doesn't fully compensate for the sleep debt you accumulate during the week.

Drinking alcohol before bed helps you sleep better

While drinking alcohol may initially make you feel sleepy or help you fall asleep faster, it can disrupt your sleep cycles and worsen your sleep quality.

Watching TV or using electronic devices helps you unwind before sleep

While some people enjoy watching TV before going to bed, the blue light emitted by screens can interfere with the production of melatonin, a hormone that regulates the sleep-wake cycle. The same goes for electronic devices such as tablets and smartphones. It's advisable to limit screen time to 1–2 hours before bedtime to optimize sleep quality.

Just like eating or drinking water, sleep is essential to life. Ignoring this basic need can have serious consequences for your physical and mental health. So, make sure you’re getting enough quality sleep. And if you’re having trouble with that, don’t hesitate to get the help you need.


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