Scottish researchers have found that increasing numbers of children are suffering "significant" injuries after falling out of bunk beds.
Researchers - who monitored victims of bunk bed accidents at the Royal Aberdeen Children's Hospital - said 85% of the injuries were sustained by children who fell out of bed while asleep.
They warned that three quarters of those injured were under the age of six and that a third of the children injured sustained bone fractures.
They are now calling for an information campaign to make parents more aware of the dangers of bunk beds.
Dr Diana Macgregor carried out the research after noticing increasing numbers of children coming in with injuries caused by falling out of bed.
Of 8,000 children attending the unit over a five-month period during 1998, 85 had injured themselves after falling from an upper bunk, bed or cot.
Twenty-seven suffered head injuries, with seven so severe that the child vomited or lost consciousness.
Ten children fell out of a lower bunk or bed while they were playing and two injured themselves jumping off a top bunk.
Fourteen (16%) required hospital admission.
Injury pattern
Children also injured themselves falling out of low beds if there was furniture nearby.
Of the 25 who had fractures, 18 were under six.
Falls from top bunks accounted for 4% of all fractures seen during that period, and those occurring in children under six accounted for 2%.
Children also suffered head injuries, lacerations or soft tissue injuries.
Most companies selling bunk beds recommend children under six should not sleep in the top bunk.
But researchers said, in spite of industry recommendations parents are either unaware of the advice or ignored it.
Safety suggestions
Dr Macgregor told BBC News Online bunk beds were a natural solution for growing families.
"Families get bigger, and if there is a shortage of space, bunk beds are ideal. Oldest children are put in the top bunk no matter how young they are."
She said children moved around more in their sleep than adults.
"Children sleep very very soundly and if they do move then they are at risk."
She said parents should make sure children sleep at the end of the bunk away from the ladder, and suggested pillows could be arranged to prevent the child falling out.
A spokeswoman for the Royal Society for the Prevention of Accidents said: "We would like to see, particularly on the top bunks, safety rails on both sides, and the ladder should be securely fastened.
"If young children are using the beds, maybe parents should consider having them both on the floor until the children are older."
John Ryan, A&E consultant at Brighton's Royal Sussex Hospital said a lot of injuries they saw in infants were part of the "occasional hazards of growing up".
He said there were ways to prevent children getting into dangerous situations, but said safety measures should be taken, and said parents should be warned not to put three-year-olds in the top bunk.
The research is published in the Injury Prevention journal.