What is sleep?

While you are sleeping your brain and body functions are still active. Sleep is a natural process that helps your body restore energy, supports learning and memory, and keeps you healthy.

During sleep, your brain cycles through different stages of non-rapid eye movement (non-REM) sleep and rapid eye movement (REM) sleep. Non-REM sleep has three stages that range from light to deep sleep, while REM sleep is when most dreaming occurs. During each stage, your brain waves, breathing, heart rate, and body temperature change throughout the night. Certain phases of sleep help you:

• Feel rested and energetic the next day.
• Learn new information, get insight, and form memories.
• Give your heart and blood vessels a rest.
• Release growth hormone, which helps children grow and assists in muscle repair and tissue healing for everyone.
• Release sex hormones, which contribute to puberty and fertility.
• Maintain a healthy balance of hormones that control hunger and fullness.
• Strengthen your immune system by producing cytokines (hormones that help the body fight infection).

You need all the stages to get a healthy sleep.

How much sleep do I need?

The amount of sleep you need depends on your age, lifestyle, health, and sleep patterns. The general recommendations for sleep are:

• Babies (4-12 months): 12-16 hours a day (including naps)
• Children (1-2 years): 11-14 hours a day (including naps)
• Children (3-5 years): 10-13 hours a day (including naps)
• Children (6-12 years): 9-12 hours a day
• Teens (13-18 years): 8-10 hours a day
• Adults (18 years and older): 7-9 hours a day

During puberty, teenagers' biological clocks shift. They tend to fall asleep later and wake up later, which can conflict with the early school start times. This is one reason many teenagers don't get enough sleep.

Some people think adults need less sleep as they age, but there is no evidence to support this. However, older adults often get less sleep or spend less time in the deep, restful stages of sleep. They also wake up more easily.

It's not just the number of hours of sleep you get that matters. The quality of the sleep you get is also important. People whose sleep is frequently interrupted might not get enough of certain stages of sleep. If you are wondering whether you are getting enough sleep, including quality sleep, ask yourself:

• Do I have trouble getting up in the morning?
• Do I have trouble focusing during the day?
• Do I doze off during the day?

If you answered yes to any of these questions, you may need to improve your sleep habits.

What are the health effects of not getting enough sleep?

Sleep is important for overall health. When you don't get enough sleep (sleep deprivation), it does more than just make you feel tired. It can impair your ability to think clearly, react quickly, and form memories. This increases your risk of making mistakes, taking risks, or getting into accidents.

Sleep deprivation can also affect your mood, leading to:

• Irritability
• Problems with relationships, especially for children and teenagers
• Depression
• Anxiety

It can also affect your physical health. Not getting enough sleep, or getting poor-quality sleep, increases your risk of:

• High blood pressure
• Heart disease
• Stroke
• Kidney disease
• Obesity
• Type 2 diabetes

Not getting enough sleep can also lower your levels of hormones that help children grow and help the body build muscle, repair tissue, and fight infections.

Sleep deprivation also magnifies the effect of alcohol. A tired person who drinks too much alcohol will be more impaired than a well-rested person who drinks the same amount.

How can I get better sleep?

You can take steps to improve your sleep habits. First, make sure that you allow yourself enough time for sleep. Getting enough sleep each night may help you feel happier and more productive during the day.

To improve your sleep habits, it also may help to:

• Go to bed and wake up at the same time every day.
• Avoid caffeine, especially in the afternoon and evening.
• Avoid nicotine.
• Exercise regularly, but not too close to bedtime.
• Avoid alcoholic drinks before bed.
• Avoid large meals and drinks late at night.
• Don't take a nap after 3 p.m.
• Relax before bed by taking a bath, reading or listening to calm music.
• Keep your bedroom cool, dark, and quiet.
• Get rid of distractions such as TVs, computers, and phones.
• Get enough sunlight exposure during the day.
• If you can't fall asleep for 20 minutes, get up and do something relaxing.
• See a health care provider if you have continued trouble sleeping. You may have a sleep disorder, such as insomnia or sleep apnea. In some cases, your provider may suggest trying a sleep study or other treatments.

If you are a shift worker, getting good sleep can be more challenging. You may also want to:

• Take naps and extend your total sleep time
• Keep the lights bright at work
• Limit shift changes to help your body adjust
• Limit caffeine to the first part of your shift
• Remove sound and light distractions in your bedroom during daytime sleep (for example, use light-blocking curtains or earplugs)