The University of Warwick in Great Britain conducted a study of 3,968 men and 4,821 women, who took part in what came to be known as the English Longitudinal Study of Ageing (ELSA).
The ELSA produced some interesting results for adults over the age of 50. For instance, among participants aged 50 to 64, short nighttime sleep (fewer than six hours) or longer nighttime sleep (more than eight hours) both resulted in test scores showing lowered brain functioning.
However, among the 65- to 89-year-old participants, reduced brain functioning occurred only in those who slept more than eight hours, not in those who slept less.
What we can draw from this is perhaps not altogether conclusive, other than the fact that all of us need at least six to eight hours of sleep a night, and that we should neither shortchange nor overdo the amount of sleep required for healthy brain (and overall bodily) functioning.
Poor sleep at all ages has been associated with obesity, diabetes, hypertension, heart problems and stroke, especially if the poor sleep originates from a sleep disorder such as obstructive sleep apnea (OSA), which is characterized by repeated cessation of breathing throughout the night.
According to many research studies, sleep plays two important roles in memory. First, without sound sleep, it is hard to focus in the daytime and therefore to absorb what is being taught or what is being experienced. Second, poor sleep at night obstructs the consolidation of the day’s activities — thus memory.
Scientists aren’t exactly sure — or agree — how sleep enhances memory, but it appears to involve the brain’s hippocampus and neocortex — the part of the brain where long-term memories are stored. It is thought that, during sleep, the hippocampus replays the events of the day for the neocortex, which reviews and processes memories, helping them endure for the long term.
At any rate, the bottom line is ensuring you sleep soundly at night. If you have difficulties sleeping — or difficulties performing well and focusing in the daytime — then you need to get back on the proper sleep track. If by adopting sound sleep-hygiene methods you still can’t get a good night’s sleep, then it’s time to seek out the professionals.