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So many of us seem to not get enough sleep, and then there are those that sleep and sleep. But .. it seems the sweet spot for sleep and our brain health (cognitive performance) is about 7 to 8 hours - at least according to a large study from Canadian researchers at Western University. People reporting typically sleeping 4 hours or less a night had the most impairments in how they performed on a variety of cognitive tests - equivalent to aging 8 years.

Reasoning, verbal skills, and overall cognition were impaired by less than 7 hours or more than 8 hours of sleep. But not short term memory. Actual age of the person made no difference on the results - everyone performed best at 7 to 8 hours of sleep. (Volunteers completed a series of 12 tests online which measured a broad range of cognitive abilities.) By the way, about half of the 10886 persons participating in the study reported typically sleeping 6.3 hours or less a night. Not enough. The good news is that just one night of sleeping a little more than the usual too little had a positive effect on cognitive abilities - thus cognitive improvement. From Science Daily:

World's largest sleep study shows too much shut-eye can be bad for your brain  ...continue reading "What Is Optimal Amount Of Sleep For Our Cognitive Processes?"

This is a nice study showing cause and effect:  6 hours of sleep or less at night lowers the body's resistance so that the person is more likely to catch a cold virus. From Science Daily:

Short sleepers are four times more likely to catch a cold

A new study led by a UC San Francisco sleep researcher supports what parents have been saying for centuries: to avoid getting sick, be sure to get enough sleep. The team, which included researchers at Carnegie Mellon University and University of Pittsburgh Medical Center, found that people who sleep six hours a night or less are four times more likely to catch a cold when exposed to the virus, compared to those who spend more than seven hours a night in slumber land.

Scientists have long known that sleep is important for our health, with poor sleep linked to chronic illnesses, disease susceptibility and even premature death. Prather's previous studies have shown that people who sleep fewer hours are less protected against illness after receiving a vaccine. Other studies have confirmed that sleep is among the factors that regulate T-cell levels.

Researchers recruited 164 volunteers from the Pittsburgh, PA, area between 2007 and 2011. The recruits underwent two months of health screenings, interviews and questionnaires to establish baselines for factors such as stress, temperament, and alcohol and cigarette use. The researchers also measured participants' normal sleep habits a week prior to administering the cold virus, using a watch-like sensor that measured the quality of sleep throughout the night.

The researchers then sequestered volunteers in a hotel, administered the cold virus via nasal drops and monitored them for a week, collecting daily mucus samples to see if the virus had taken hold. They found that subjects who had slept less than six hours a night the week before were 4.2 times more likely to catch the cold compared to those who got more than seven hours of sleep, and those who slept less than five hours were 4.5 times more likely.