Washington, June 9 : Genetic factors behind increased sleep problems during times of stress are the same as those responsible for intrusive and ruminative thoughts leading to insomnia in people, according to a study.

The findings of the study indicate that sleep reactivity to stress is what controls the genetic relationship between ruminative thoughts (unwanted thoughts that are difficult to control) and insomnia.

The results underline the importance of revealing the influences of sleep reactivity on ruminative thoughts and insomnia.

Lead author Dr. Naomi Friedman, at the Institute for Behavioural Genetics at the University of Colorado at Boulder, said that the substantial genetic predispositions to these problems may be modifiable.

And thus treatments designed to reduce sleep reactivity to stress might have the potential to improve insomnia related to rumination.

"Identification of genes underlying the association between sleep reactivity to stress and intrusive thinking and ruminative tendencies may enable the development of more targeted pharmacological interventions for insomnia. At the nonpharmacological level, behavioral treatments could be designed to target specific aspects underlying a tendency towards rumination in the individual across many potential environmental triggers," said Friedman.

The study included 1782 individual twins (1059 females, 723 males) between the ages of 18 and 30 years. Genetic analyses included 744 complete twin pairs (377 monozygotic and 367 dizygotic).

Participants completed an online sleep survey and questionnaires that measured sleep response to stress, frequency of intrusive thoughts, and frequency and severity of three insomnia symptoms (difficulty falling asleep, staying asleep and non-refreshing sleep).

The researchers found that females included in the study had a higher prevalence of insomnia, more frequent intrusive thoughts, and higher sleep reactivity to stress.

The degree to which genetics influenced each of these traits was not significantly different for males and females, and the relationships among these variables were similar for males and females.

The study will be presented at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies. (ANI)