What's covered
Key facts
Lack of sleep makes it harder to concentrate and pay attention.
Phones, tablets and other screens give off blue light, which is the type of light that makes you feel alert.
One full sleep cycle lasts about 90 minutes and repeats through the night.
The body clock runs on a cycle of about 24 hours, roughly one day.
During sleep the body repairs tissues, muscles and cells that were used during the day.
A tired brain finds it harder to take in and learn new information.
The body clock uses light and darkness to decide when you should feel awake or sleepy.
Most people go through about four to six sleep cycles each night.
The body clock is your body's own internal clock that controls when you feel sleepy and awake.
Growth hormone, which helps your body grow and repair itself, is mostly released during deep sleep.
Sample questions
A taste of the 50 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
About how many hours of sleep do teenagers need each night?
- •11 to 12 hours
- •4 to 5 hours
- •6 to 7 hours
- ✓8 to 10 hours
Which hormone makes you feel sleepy and helps your body get ready for bed?
- •Adrenaline
- •Dopamine
- •Insulin
- ✓Melatonin
What do the letters REM in REM sleep stand for?
- •Rapid energy mode
- ✓Rapid eye movement
- •Rested every morning
- •Resting eye movement
About how long is one full cycle of the body clock?
- •About 12 hours
- ✓About 24 hours
- •About 48 hours
- •About 8 hours
Roughly how many hours of sleep do most teenagers need each night?
- •11 to 13 hours
- •4 to 5 hours
- •6 to 7 hours
- ✓8 to 10 hours
What does a lack of sleep make harder to do in lessons?
- •Breathe air
- ✓Concentrate
- •Hear sounds
- •Stand upright
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