Menstruation, pregnancy and the menopause were all rated as reasons why women suffer restless nights.

The US National Sleep Foundation found that half of all women complain that menstrual cramps and bloating disturb their sleep for two days a month.

Hot flushes during menopause mean five days of interrupted sleep a month.

Kathryn Lee, a nurse at the University of California who took part in the research, said: "This study quantifies at last how conditions unique to women are associated with sleep-related problems such as insomnia.

"During all life cycle stages insomnia, or difficulty falling and staying asleep, is a significant problem."

The survey, of more than 1,000 women found that 79% complained their sleep was disturbed more while they were pregnant.

Daytime naps

No period pain, no pregnancy....

More than half of women who were pregnant or who had recently given birth said they took at least one nap a day during the week and on some weekends.

The survey found that 36% of women going through menopause lost sleep due to hot flushes and other symptoms.

Many women said they drink caffeine to stay awake after a poor night's sleep.

However, experts advise staying away from coffee, sodas and other caffeinated drinks.

The best way to ensure a good night's sleep, the foundation says, is to exercise during the day, and to take time to wind down before going to bed. Napping during the day is not advised.

Professor Jim Horne, director of the Loughborough University Sleep Research Laboratory, said there was no strong evidence of any difference in sleep disturbance between men and women.

He said: "Men and women sleep pretty much the same. It is just that women are more likely to admit to problems whereas men deny them."

Professor Horne said people tended to suffer from disturbed sleep more as they got older.