PEOPLE with sleep apnoea struggle to remember details from their past, making them vulnerable to depression, according to Victorian researchers.
A new study led by RMIT University has found people with obstructive sleep apnoea (OSA) struggle to remember biographical memories which can make them more vulnerable to depression.
OSA is a serious condition that occurs when a person’s breathing is interrupted during sleep, and affects almost a third of elderly people.
The study examined how OSA affected people’s autobiographical memory and found those with untreated OSA 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.
“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,” she said.
“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.”
The study compared 44 adults with untreated OSA to 44 healthy controls, assessing their recall of different types of autobiographical memories from their childhood, early adult life and recent life.
The results showed people with OSA had significantly more overgeneral memories.
Overgeneral autobiographical memory is an inability to retrieve specific memories from one's autobiographical memory. Instead, general memories are recalled, such as repeated events.
It found those with OSA also struggled with semantic memory (facts and concepts from personal history like the names of school teachers), but their episodic memory (events, or episodes, like the first day at high school) was preserved.
Across both groups, being older was associated with having a higher number of overgeneral autobiographical memories.
The study was conducted with collaborators from the Institute for Breathing and Sleep, Florey Institute of Neuroscience and Mental Health and University of Melbourne.
About sleep apnoea
- Sleep apnoea occurs when the muscles in the upper airway collapse during sleep, blocking off the airway above the voice box.
- Breathing stops for a period of time (generally between 10 seconds and up to 1 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.
- It’s estimated that about five per cent of Australians suffer from sleep apnoea.
- Around one in four men over the age of 30 years have some degree of sleep apnoea, making it more common than asthma.
- Conservative treatment includes weight loss and cutting back on alcohol.
- Active treatment includes nasal CPAP, mouthguards or surgical correction of upper airway obstruction.
- Daytime sleepiness may distinguish simple snorers from people with sleep apnoea
Read more: Never underestimate the power of sleep
