Three questions that tell you whether you are sleeping enough

While you sleep, your brain and body are still working. Sleep restores energy,
supports learning and memory, and keeps you healthy. Your brain cycles through
three stages of non-REM sleep, from light to deep, and REM sleep, where
most dreaming happens — with brain waves, breathing, heart rate and body
temperature changing through the night.

You need all the stages for healthy sleep. Different phases do different
jobs:

• Feeling rested the next day
• Learning, insight and forming memories
• Giving the heart and blood vessels a rest
• Releasing growth hormone — which helps children grow, and helps everyone
  repair muscle and heal tissue
• Releasing sex hormones, contributing to puberty and fertility
• Keeping the hormones that control hunger and fullness in balance
• Strengthening the immune system by producing cytokines

How much

Two corrections worth carrying:

Teenagers are not lazy. During puberty the biological clock shifts: they
fall asleep later and wake later, **which conflicts with early school start
times**. That is one reason many teenagers do not get enough sleep.

Adults do not need less sleep as they age. There is no evidence for it.
Older adults often get less, or spend less time in deep restful stages, and
wake more easily — but the requirement has not changed.

The three questions

Hours are not the whole story. **People whose sleep is frequently interrupted
may not get enough of certain stages**, even at the right total.

So ask:

1. Do I have trouble getting up in the morning?
2. Do I have trouble focusing during the day?
3. Do I doze off during the day?

Yes to any one of them means your sleep habits need work.

What too little sleep does

It impairs clear thinking, quick reaction and memory formation, raising the
risk of mistakes, risk-taking and accidents. It affects mood — **irritability,
relationship problems (especially in children and teenagers), depression,
anxiety**.

And physically, too little or poor-quality sleep raises the risk of **high
blood pressure, heart disease, stroke, kidney disease, obesity and type 2
diabetes**, and lowers the hormones that help children grow and help the body
build muscle, repair tissue and fight infection.

One specific effect worth knowing: **sleep deprivation magnifies the effect of
alcohol.** A tired person who drinks too much will be more impaired than a
well-rested person who drinks the same amount.

Improving it

First, allow yourself enough time for sleep — the most-skipped step. Then:
go to bed and wake at the same time every day, and **avoid caffeine,
especially in the afternoon and evening**.

Source: MedlinePlus, U.S. National Library of Medicine.