Memory being lost during apnoea episodes
SLEEP apnoea is not just about suffering through poor sleep and breathing problems, it's now been found to affect people's memories.
A new study led by RMIT University looked at how obstructive sleep apnoea (OSA) affected autobiographical memory. It found that people with untreated with the conditions had problems recalling specific details about their lives.
Lead investigator Dr Melinda Jackson said the research built on the known links between depression and memory.
"We know that overly general autobiographical memories - where people don't remember many specific details of life events - are associated with the development of persistent depression," Dr Jackson said.
"Our study suggests sleep apnoea may impair the brain's capacity to either encode or consolidate certain types of life memories, which makes it hard for people to recall details from the past.
"OSA is increasingly common, affecting up to 30 per cent of elderly people and around one in four Australian men aged over 30.
"Sleep apnoea is also a significant risk factor for depression so if we can better understand the neurobiological mechanisms at work, we have a chance to improve the mental health of millions of people."
About five per cent of Australians suffer from sleep apnoea.
The BetterHealth Channel describes it as when a person's breathing stops for a period of time, generally between 10 seconds and up to one minute, until the brain registers the lack of breathing or a drop in oxygen levels and sends a small wake-up call. The sleeper rouses slightly, opens the upper airway, typically snorts and gasps, then drifts back to sleep almost immediately. This pattern can repeat itself hundreds of times a night, causing fragmented sleep.
The recommended treatment for OSA includes weight loss and cutting back on alcohol. Active treatment includes nasal CPAP, mouthguards or surgical correction of upper airway obstruction.
Dr Jackson said the use of CPAP machines to treat sleep apnoea had improved some of the cognitive impairments related to the condition.
"An important next step will be to determine whether successful treatment of sleep apnoea can also help counter some of these memory issues or even restore the memories that have been lost," she added.
The study was conducted in collaboration with the Institute for Breathing and Sleep, Florey Institute of Neuroscience and Mental Health, and University of Melbourne and published in Journal of the International Neuropsychology Society.