Whereas higher educational attainment improved women's night time sleep quality, it had the opposite effect on men.

Conversely, the better educated a man is, the less likely he is to get a good night's sleep, the research shows.

The findings, published in the Journal of Epidemiology and Community Health, are based on a nationally representative Taiwanese survey on social trends, involving nearly 40,000 people aged 15 and older.

Questions included marital status, employment/occupation, educational attainment, and household income, as well as the number of family members under the age of 15. Insomnia was assessed using criteria developed by the World Health Organization, and scored on a scale of 1 to 5.

Divorce, Separation Take Night-Time Toll

Overall, insomnia tended to be more common among those who were older, divorced/separated, had low educational attainment, poor health or low income. Children living at home also increased the rates of insomnia.

These findings applied to both sexes, but rates of insomnia still were significantly higher among women, who averaged 1.22 more points on the insomnia scale than men.

Sex differences in insomnia score were most noticeable for divorced/separated women. The stress associated with single parenthood, loss of income, or the stigma of a marriage break-down could be possible factors, suggest the authors.

Unemployment Robs Women of Sleep

Unemployment also exerted a greater impact on women's sleep quality -- particularly for married women. Sex discrimination in the workplace and childcare responsibilities might account for this, suggest the authors.

Whereas higher educational attainment improved women's night time sleep quality, it had the opposite effect on men.

Globally, women may be twice as likely to be insomniac as men, say the authors. Social factors undoubtedly play their part, but do not fully explain these differences, they add.