The Ideal Amount of Sleep Is... least six hours and no more than eight hours.

The consequences of sleeping less or more than this can be dire--especially for middle-aged adults. Regularly sleeping less than six hours or more than eight hours is linked to a decline in brain function, according to British researchers at the University College London Medical School.

HealthDay News reports that the magnitude of this sleep-induced mental decline is equal to being four to seven years older than your real age.

"There is an expectation in today's 24-hour-a-day society that people should be able to fit more into their lives," lead study author Jane Ferrie, who is a senior research fellow in the department of epidemiology and public health at University College London Medical School, told HealthDay News. "The whole work/life balance struggle is causing people to trade in precious sleeping time to ensure they complete everything they feel is expected of them. Our study suggests that this may have adverse effects on their cognitive function."

The study: The British team collected data on 5,431 men and women, all of whom were ages 35 to 55 in 1985 and were part of the Whitehall II study, a long-term examination of London-based office workers. From 1997 to 1999, the team asked each participant how many hours he or she slept on an average week night. The same question was asked again in 2003 to 2004; at this time, the participants were given a battery of standard tests to assess memory, reasoning, vocabulary, global cognitive status and verbal fluency.

The results:

  • Women who slept seven hours a night had the highest score on every cognitive measure, followed by women who had six hours of sleep.

  • Men who slept six, seven or eight hours had similar cognitive function.

  • Men and women who slept less than six hours or more than eight hours had far lower cognitive scores than those who slept around seven hours.

Many biological processes take place while we sleep. Ferrie told HealthDay News, "Sleep provides the body with its daily need for physiological restitution and recovery. While seven hours a night appears to be optimal for the majority of human beings, many people can function perfectly well on regular sleep of less or more hours."

People who regularly sleep too little risk serious disease, since chronic short sleep produces hormones and chemicals in the body that increase the risk of developing heart disease and strokes, as well as high blood pressure, high cholesterol, diabetes and obesity.

The takeaway: Turn off the TV and go to bed! Getting enough sleep every night--and not just on the weekend--is an essential part of good health and well being. In fact, it is just as important as eating well and staying physically active.

The study findings were published in the journal Sleep.

--From the Editors at Netscape

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