Workers at a chain of budget hotels are being given advice on how to deal with naked sleepwalkers.

It follows an increase in the number of guests found wandering around in the night with no clothes on.

A study by Travelodge found there had been more than 400 cases in the past year, almost all involving men.

Sleep experts blame stress, alcohol abuse and lack of sleep for the disorder.

The research, conducted in 310 Travelodge hotels, found sleepwalkers wandered all over the building.

A number had walked into the reception area asking for a newspaper or saying they wanted to check out.

Travelodge said it was sending notes to its staff on how to deal with the problem.

The advice includes keeping a supply of towels in reception to help preserve a guest's dignity.

Chris Idzikowski, an expert at the Edinburgh Sleep Centre, said: "These figures are a surprise.

"Sleepwalking is most likely within an hour or two of going to bed, when first slipping into a deep sleep.

"Part of the brain switches into autopilot and can manage well-learned movements such as walking, bending or sitting."

He added: "Sleepwalkers will awake quite unable to recall any of their actions."

The study also found one in 10 sleepwalkers had injured themselves on their travels.