What Happens to Your Body During Sleep?
We know that sleep is essential. Individuals born with the genetic inability to sleep will die within a year of developing their symptoms. All animal organisms have some state similar to human sleep.
The benefits of sleeping include cleansing the brain of built-up toxins, enhancing memory, improving mood, and conserving metabolism. Experts recommend 7 to 9 hours of sleep nightly.
There is no benefit to sleeping little most of the week and “catching up” on the weekends. This recommendation is based on research showing poorer health outcomes when you sleep less than 7 hours nightly.
The Different Stages of Sleep
Sleep is not the same from the time you begin to sleep until you awaken. There are, instead, different sleep stages that often operate in 90-minute cycles. However, the first half of sleep is dominated by more deep or restorative sleep, while the latter half of the night is dominated by dream sleep, called REM.
These are the various stages of sleep:
- Light sleep – This includes sleep in the early stages, when you are drowsy and get into a sleeping rhythm. At least half of regular sleep is light sleep, partly because it is part of a pattern of alternating light, deep, and REM sleep.
- Deep sleep – Deep sleep is sometimes called “restorative” sleep or non-REM sleep. It is when you are more likely to have your body restore itself and for your brain to flush itself of toxins.
- Dream/REM sleep – The term “REM” means rapid eye movement sleep. Your partner will notice rapid eye movements or eye fluttering to indicate that you are dreaming. You can dream in non-REM sleep, but this is less common.
The Role of Sleep in Overall Health
Sleep is essential, particularly deep sleep. If you don’t get any REM sleep, you will have mood disturbances and other issues, but you probably won’t die. If you don’t get deep sleep, on the other hand, you will die of mental and physical decline.
Enough sleep means you will likely have reduced appetite, lower weight, better mood, better concentration, better physical performance, and lower blood pressure.
Sleep-deprived individuals will often have an immediate decline in mental function; long-term lack of sleep will lead to adverse physical effects on your vital signs and weight.
Factors that Influence the Amount of Sleep Needed
How much sleep you need is mostly fixed. Genetic variations exist in how much sleep you need; however, requiring less than 6 hours or more than 10 hours of sleep is extremely rare. Almost everyone functions at 7 to 9 hours of nightly sleep.
Recommended Sleep Duration for Different Age Groups
Your age also matters in how much sleep you get. Babies sleep longer than adults because they need sleep to preserve energy and allow the brain to develop correctly.
The CDC offers this advice for the amount of sleep you need per night by age:
- Newborns – 14 to 17 hours
- Infants up to 12 months – 12 to 16 hours
- Toddlers – 11 to 14 hours
- Preschoolers – 10 to 13 hours
- School age – 9 to 12 hours
- Teens – 8 to 10 hours (they will also do better if they sleep in for part of the morning hours)
- Adults – 7 to 9 hours (after age 65 years, 7-8 hours are sufficient; many older adults awaken earlier than normal for them).
Effects of Sleep Deprivation
Sleep deprivation quickly takes a toll. The longest known time without sleep was documented in 1963 when Randy Gardner lasted 11 days and 25 minutes.
He and others who have done this developed psychosis, extreme mood changes, and mental cognition changes – some of which lasted beyond the sleep deprivation experiment.
If you get insufficient sleep for longer than a few days, you will build up a sleep debt that you cannot effectively make up by sleeping longer later. Long-term sleep deficiency leads to higher levels of depression, obesity, high blood pressure, stroke, heart disease, and kidney disease.
Debunking the Myth of 6-Hour Sleep
There is a lot of evidence that lack of sleep harms your physical and mental health. Is there evidence to support sleeping just 6 hours per night, or is that too little sleep?
Studies and Research Supporting the Need for More Than 6 Hours of Sleep
The research supporting the need to sleep more than 6 hours of sleep is extensive. Research on the mental and physical damage to your health shows a cutoff below which the increased risk to health shows up.
Below the recommended 7 hours of sleep per night, you will begin to feel sleepier during the day and will see the long-term effects of too little sleep.
Negative Effects of Consistently Getting Only 6 Hours of Sleep
The adverse effects of getting too little sleep are many. As little as 6 hours of consistent sleep can lead to mental and physical adversities:
- Poor memory and ability to learn
- Low mood or depression
- Diabetes
- Obesity
- Cardiovascular disease (stroke and heart attack)
- Kidney disease (from multiple causes)
- Early death from all causes
- Increased risk of accidents and injuries
Individual Differences in Sleep Needs
Age is a determinant of sleep need in all individuals. Individuals of the same age, however, will have different sleep needs. You will need more sleep if you are sick, training, or recovering from illness. Increased mental energy means you’ll need more sleep, too.
Genetics determines who needs more or less sleep. It also determines whether you are a morning or evening person. Morning people naturally awaken at the same time, even on their days off.
They tend to get up early. Evening people find themselves better able to think and function in the afternoon and evening.
Tips for Determining Your Ideal Sleep Duration
How do you know how much sleep you should have? Most people need the recommended 7 to 9 hours of sleep. There are a few ways to determine how much (and when) you should sleep.
Standard DNA testing for places like 23 and Me will tell you if you are a morning or evening person; however, you can take the Morningness-Eveningness Questionnaire (MEQ) to see your “chronotype.”
You can also take the Epworth Sleepiness Scale to see if you are getting enough sleep. Too much daytime sleepiness impacts driving, using heavy machinery, and everyday functioning. If you score too high, you may benefit from a sleep evaluation if you get the recommended 7 to 9-hour sleep duration.
Strategies for Improving the Quality of Your Sleep
How can you get enough sleep each night? These are some tips that may help:
- Go to bed at the same time every night; this sets your circadian rhythm (body clock) to be the same every day.
- Practice sleep hygiene by sleeping in a bedroom with the TV off and reduced light and noise. Your brain needs to settle down before sleeping through meditation or with white noise machines for better comfort during the night.
- If you struggle with sleep loss, try to sleep during the nighttime hours and don’t do shift work where your nighttime hours change.
- Don’t use screens like tablets, computers, and phones before bedtime. Your eyes see the blue light in these objects, which arouses you too much before sleep.
- Avoid sleeping pills or alcohol that may make you tired but will affect your level of sleep. You will definitely sleep, but deep sleep is reduced.
- Try yoga, a nice walk, or meditation before bedtime to get better sleep.
- Avoid heavy meals before sleeping.
- Naps may help because there is more deep sleep when napping. Use this option as a last resort, however.
FAQs
How can I tell if I’m getting enough sleep?
The best way to know if you are getting enough sleep is to measure your sleep and plan to get enough. Most fitness watches will track your sleep and tell you when you’ve slept enough. The other option is to take the Epworth Sleepiness scale and see if you feel like you have gotten enough sleep.
How can I improve my sleep quality?
There are many tools you can use to enhance sleep quality. The best option is practicing strict sleep hygiene and practicing yoga or meditation before bedtime to become sleepier.
Remember to reduce screen time in the 2 hours before bedtime and to keep a sleep environment that is conducive to excellent sleep. Some sleep experts recommend a warm bath before bedtime or cold showers to help enhance sleep quality.
Can naps replace a full night’s sleep?
A nap can never replace a full night of sleep; however, it can help you feel less sleepy. A nap leans heavily toward deep, restorative sleep, which makes them satisfying and helps reduce your sleep debt.
