Ask Me Everything7

Why do you

need to sleep?

No one knows for certain, but most scientists believe that during sleep the brain organizes, processes and Stores information, and produces memories. It also gives your body time to rest. If you don’t get enough sleep, you can become irritable and find it difficult to concentrate.

How to: sleep

WEIRD OR WHAT?

Diaries from the days before the electric light bulb was invented reveal that our ancestors slept longer

hours than we do. Maybe the light bulb wasn’t such a bright idea!

w I ■ Lie down, shut your eyes, and relax your muscles. Don’t worry if your muscles occasionally twitch or jerk. This is perfectly normal.

w A ■ Slow down your brainwaves from active beta waves to the morę relaxed alpha waves.

Slow down your breathing and reduce your body temperaturę. You will only roli over occasionally, so slow down your heart ratę.

Enter nonrapid eye movement (NREM) sleep by slowing your brainwaves from alpha to delta. It should be really difficult to wake you now.

■ At severa! points during the night, raise brainwave level back up to alpha to enter rapid eye movement (REM) sleep. This is the time to dream.

The electrical activity of brain cells can be Sleep pattem

measured using special eąuipment.

The main waves are known as beta

(consciously alert), alpha (physically and mentally relaxed), theta (sleeping with iuced consciousness), and delta (deep sleep).

age

hoiirs per day

5-12years    10-11

How much sleep?

newborns	10.5-18
3-11 months	q_h o (plus several ^1 ^ naps)
1-3 years	12-14
3-5 years	11-13

11-17 years    8.5-9.25

adults    7-9

Each night you repeat the NREM and REM stages about every 90 minutes until you wake up. The REM periods become a little longer as the night passes, which is why your longest dreams happen in the morning. During REM sleep, muscles are paralysed so you can’t act out your dreams.

NONREM    REM SLEEP

SLEEP

(c) 2011 Dorling Kindersley. Ali Rights Reserved.