Study shows that consistently sleeping seven or eight hours per night is optimal for health

Dec 3 2007

A study published in the December 1 issue of the journal SLEEP is the first to show that both a decrease and an increase in sleep duration are associated with an elevated risk of mortality by cardiovascular and non-cardiovascular means, respectively.

The study, authored by Jane E. Ferrie, PhD, of the University College London Medical School in London, U.K., focused on 10,308 participants between 35 and 55 years of age. Baseline screening (Phase 1), conducted between 1985 and 1988, involved a clinical examination and a self-administered questionnaire. Data collection at Phase 3 (1992-1993) also included a clinical examination (8,104 participants) and questionnaire (8,642 participants).

According to the results, U-shaped associations were observed between sleep at Phase 1 and Phase 3 and subsequent all-cause, cardiovascular and non-cardiovascular mortality. A decrease in sleep duration among participants sleeping six, seven or eight hours at baseline was associated with a 110 percent excess risk of cardiovascular mortality. However, an increase in sleep duration among those sleeping seven or eight hours at baseline was associated with a 110 percent excess risk of non-cardiovascular mortality. Adjustment for the socio-demographic factors, existing mortality and health-related behaviors measured left these associations largely unchanged.

“In terms of prevention, our findings indicate that consistently sleeping seven or eight hours per night is optimal for health,” said Dr. Ferrie. “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.”

On average, most adults need seven to eight hours of sleep each night to feel alert and well-rested.

The American Academy of Sleep Medicine (AASM) offers the following tips on how to get a good night's sleep:

• Follow a consistent bedtime routine.
• Establish a relaxing setting at bedtime.
• Get a full night's sleep every night.
• Avoid foods or drinks that contain caffeine, as well as any medicine that has a stimulant, prior to bedtime.
• Do not go to bed hungry, but don't eat a big meal before bedtime either.
• Avoid any rigorous exercise within six hours of your bedtime.
• Make your bedroom quiet, dark and a little bit cool.
• Get up at the same time every morning.

Those who believe they have a sleep disorder should consult with their primary care physician or a sleep specialist.