THE aroma has been described as a cross between stinky socks and a gerbil’s cage. Now a sleep expert has warned that the smelliness of a teenager’s bedroom is a factor in insomnia, which has been linked to low exam grades.

Colin Espie, professor of sleep medicine at Oxford University, said teenagers will be given advice on “bedroom hygiene” as part of a nationwide study into concerns that youngsters are so sleep-deprived that it is affecting their academic performance and mental wellbeing.

“Young people never open their windows, their rooms are never ventilated,” said Espie.

“The smelly teenager’s bedroom is a byproduct of the fact that the room is full of rebreathed air, which is low in oxygen and high in nitrogen. If you keep