Lazy bone or hyperactive? If you do not sleep on average 7-8 hours per night, in the end both less or more than this could cut short your life, as found by a new research carried on at the University College London Medical School, in London, U.K., and published in the journal "SLEEP", revealing for the first time that a decrease and an increase in sleep duration are connected with higher mortality because of cardiovascular and non-cardiovascular issues.

The research was made on 10,308 subjects aged 35 to 55. Phase 1, carried on between 1985 and 1988, included a clinical examination and a self-administered questionnaire. Data gathering at Phase 3 (1992-1993) consisted in clinical examination (8,104 subjects) and a questionnaire (8,642 subjects). There was a Gaussian curb (U-shaped) relationship seen between sleep duration at Phase 1 and Phase 3 and mortality, no matter of cardiovascular or non-cardiovascular issues.

Lowered sleep duration in subjects sleeping six, seven or eight hours, during Phase I, was linked to a 110 % increased likelihood of cardiovascular mortality, while higher sleep duration in subjects with seven or eight hours sleep duration, during Phase I, was connected to a 110 % higher vulnerability for dying of non-cardiovascular diseases. These values were not significantly changed by considering the socio-demographic factors, overall mortality and lifestyles.

"In terms of prevention, our findings indicate that consistently sleeping seven or eight hours per night is optimal for health. The indication that mortality rates are lower in participants who slept five to six hours or less at Phase 1 but who reported extended hours of sleep at Phase 3 implies that increasing sleep duration in short sleepers is likely to have health benefits.

In contrast to this, the finding that an increased duration of sleep among those sleeping seven to eight hours is associated with higher levels of mortality implies that sleep restriction should at least be considered", said author Dr. Jane E. Ferrie.