Insomnia is common in Spain, and affects one person in every five. This is the conclusion of a study carried out by the Vall d'Hebron University Hospital in Barcelona and the Stanford University School of Medicine (USA), which shows that 40% of survey respondents aged over 65 report interrupted sleep at night being the prime cause of this problem.

"Good sleep hygiene is necessary in order to avoid primary insomnia, as well as being aware that the number of hours of sleep needed falls with age, adopting regular times for going to bed and getting up, and stopping having an afternoon nap", Teresa Sagalés, one of the authors of the study and formerly head of the Clinical Neurophysiology Department at the Vall d'Hebron University Hospital in Barcelona, tells SINC.

Sagalés, along with Maurice M. Ohayon from the Stanford University School of Medicine (USA), has studied the prevalence of insomnia among the Spanish population by using a survey of 4,648 individuals aged over 15. The results, which are currently the most recent to have been published, from February 2010, show that one in five people suffer from this sleep alteration.

17.6% of the individuals say that interrupted sleep is the prime cause of their insomnia, in particular people aged over 65 (40%), while 3.7% say they have difficulty going to sleep and 4.3% wake up very early and find it hard to go to sleep. In both cases these problems are more common among women.

Difficulty in falling asleep increases with age, and affects 10% of people aged over 55. Overall, 6.4% of people were diagnosed with insomnia, with differences according to gender (7.8% of women and 4.9% of men) and age (3.3% of younger people and 9.8% of those aged over 65).

"Individual sleep studies using polygraphic techniques are not useful for discovering the degree to which insomnia is a problem among the general population. We need to use surveys that have been rigorously carried out and cover a large enough number of subjects", the expert explains.

In this study, published in Sleep Medicine, a formal diagnosis of insomnia was made by using data from the survey and the criteria used in the diagnostic and statistical manual of mental disorders (DSM-IV) produced by the American Psychiatric Association.