It may be that someone who is anxious would wake up feeling upset and feel hungry

Linda Blair

The body's 24-hour clock is regulated by a complex pattern of hormones, which also play a role in how the body responds to stress.

The researchers set out to test the theory that a compulsion to eat at night indicates a disruption of this hormone pattern - and consequently an inability to deal with stress.

They compared five women with night-eating syndrome with five women who had no such compulsion to eat at night.

The women with the syndrome ate at least half of their daily intake of food after 8pm, and snacked at least once during the night.

Tests revealed that the night eaters had significantly higher levels of the stress hormone cortisol in their blood.

Similar findings have been recorded in people with other disorders, such as obesity, fatigue syndrome, anorexia nervosa, insomnia and depression.

Comfort

However, it is not yet clear whether these disorders are all caused by the same disruption to hormone patterns.

Linda Blair, a clinical psychologist at the University of Bath who specialises in stress, told BBC News Online that the study was interesting, but did not prove cause and effect.

She said: "It certainly makes sense. One of the most common symptoms reported by anxious people is that they have problems with sleep disturbance, and an awful lot of people use food as a way of comforting themselves.

"It may be that someone who is anxious would wake up feeling upset and feel hungry, not realising that they were using food as a way to comfort themselves."

Age problems

A second study has shown changes to hormone production may explain why getting a good night's sleep can become more difficult with age.

Research suggests that more than 50% of older people have sleep problems, and up to one in three have trouble maintaining sleep on a regular basis.

New research by scientists at Harvard Medical School suggest the culprit may be the hormone melatonin.

It appears that as people get older, the time that they secrete melatonin is shunted forward.

This could explain why they get tired earlier in the evening, and have trouble sleeping past the small hours of the morning.

Both studies are published in the American Journal of Physiology.