With less sleep, normal aging-related structural changes in the brain progress slightly faster in middle-aged and older people, according to a new brain imaging study conducted by the Duke-NUS Graduate Medical School in Singapore
Sleep troubles are more common with age, and shrinkage of certain brain structures is normal. But for the over-55 study participants, those changes could be seen accelerating slightly with each hour less of sleep each night.
Plenty of past research has shown that lack of sleep can worsen fuzzy thinking and memory problems in the short term, and at all ages, Lo and her colleagues note in the journal Sleep.
Fewer studies have looked at physical changes in the brain and their link to sleep over time, the report points out. And none have done it for older adults, according to the researchers.
To assess the effects of sleep duration on both thinking and brain structure, the study team analyzed data on healthy people over age 55 participating in the larger Singapore Longitudinal Aging Brain Study.
Researchers looked at data on 66 Chinese adults who had previously undergone magnetic resonance imaging (MRI) scans to measure brain volume in specific areas and had taken tests to assess their cognitive skills.
The researchers used questionnaires to determine participants’ sleep duration and quality, and measured blood levels of high sensitivity C-reactive protein, an indicator of inflammation.
When the cognitive tests and scans were repeated two years after the initial round, the researchers found those participants who slept fewer hours showed evidence of faster brain shrinkage and declines in cognitive performance.
The ventricles are fluid-filled spaces in the brain, and they expand as the brain ages, indicating a shrinkage of brain tissue. Faster ventricle enlargement is a marker for cognitive decline and the development of neurodegenerative diseases such as Alzheimer’s, according to the authors.
For each hour less participants slept, on average, the rate of ventricle enlargement rose by 0.59 percent, after adjusting for other individual factors like weight, age, sex and education.
And for each hour less of sleep, the decline in cognitive performance increased by 0.67 percent – though the researchers caution that result was more variable and should be considered preliminary.
The study cannot prove that total sleep time caused the changes observed. Although the study subjects were free of any major diseases or diagnoses, the researchers did not determine, for example, if other factors that might affect both brain structures and sleep duration could account for the results.
The reasons why shorter sleep time might affect brain changes are still a bit of a mystery, but there are several possible mechanisms.
Some have proposed that sleep loss increases inflammation which has a negative impact on the brain, but our own data do not support this view. Alternatively, short sleep is associated with other medical conditions which may accelerate brain aging.
As we age, our sleep mechanisms weaken so it’s harder to get to sleep, but there are things people can do to improve sleep.
Avoid napping during the day, have a firm routine as far as going to bed at the same time, get up at the same time and try to ensure that we get to sleep by following good sleep hygiene techniques.
The sleep environment should be dark, cool and quiet enough for sleep and that the mattress should be comfortable. In addition, we suggest avoiding alcohol, cigarettes and exciting activities close to bedtime.