Sleep Helps Our Memory

sleeping-womanEvery night, while we lie asleep, blind, dumb and almost paralyzed, our brains are hard at work. Neurons in the sleeping brain fire nearly as often as they do in a waking state, and they consume almost as much energy. What is the point of this unceasing activity at a time when we are supposedly resting? Why does the conscious mind disconnect so completely from the external environment while the brain keeps nattering on?

The brain’s activity during rest likely serves some essential function. The evidence for this importance starts with sleep’s ubiquity. All animals apparently sleep even though being unconscious and unresponsive greatly raises the risk of becoming another creature’s lunch. Birds do it, bees do it, iguanas and cockroaches do it, even fruit flies do it, as we and others demonstrated more than a decade ago.

Sleep must serve some vital function because all animals do it. Evidence suggests that sleep weakens the connections among nerve cells, which is a surprising effect, considering that strengthening of those connections during wakefulness supports learning and memory. But by weakening synapses, sleep may keep brain cells from becoming oversaturated with daily experience and from consuming too much energy.

Do Sleep Patterns Affect the Risk of Cognitive Decline?

Older CoupleVANCOUVER—The quality and quantity of sleep may be associated with the risk for cognitive decline, according to four studies presented at the 2012 Alzheimer’s Association International Conference. Treatments for insomnia or circadian rhythm delay might reduce or prevent cognitive decline, investigators reported.

Sleep Duration and Cognition
Compared with a sleep duration of seven hours per day, sleep durations of five or fewer hours per day and of nine or more hours per day were associated with worse average memory at older ages, according to Elizabeth Devore, ScD, Associate Epidemiologist at Brigham and Women’s Hospital in Boston. Short and long sleep durations at midlife and in later life were both associated with worse memory in later life. [Read more…]