Last updated at 14:51 GMT, Thursday, 10 March 2011

Sleepwalking

Man asleep in his bed

Sleepwalking is usually harmless

Alice and Stephen talk about people who sleepwalk, and how scientists believe the condition is passed on from parent to child.

This week's question:

What do the letters REM stand for?

a) rapid eye movement

b) random eye movement

c) relative eye movement

Listen out for the answer at the end of the programme!

Listen

Sleepwalking

End of Section

Grammar

sleepwalk

do things while asleep, e.g. walk around

genetic

inherited; a feature that someone was born with that was passed on by their parents or grandparents

genes

parts of living cells which carry information about physical characteristics, e.g. a person's appearance and health

doses of medication

specific amounts of medicines taken at regular times, as instructed by a doctor

harmless

not dangerous

it runs in families

it is a feature or condition that affects several people who are related

generations

here, members of a family who are directly related through their parents, grandparents, great grandparents etc

defective

faulty, imperfect

fifty-fifty

two equal possibilities