Undiagnosed sleep apnoea is being blamed for high rates of cardiovascular disease and memory loss among people with schizophrenia.
Researchers from the University of Adelaide in South Australia in collaboration with Lyell McEwin Hospital have shown that people with schizophrenia are more likely to develop severe obstructive sleep apnoea.
The research, which incorporated home sleep studies on 32 patients with schizophrenia, is the first of its kind worldwide to confirm a link between schizophrenia and obstructive sleep apnoea.
Lead researcher Hannah Myles said 45 per cent of the patients in the study were diagnosed with sleep apnoea and eight of them were diagnosed with severe sleep apnoea.
She said the results showed that many symptoms previously thought to have been caused by schizophrenia or medication could have been caused by sleep apnoea instead.
"We found that they had very high rates of sleep apnoea - about three times more likely to have severe sleep apnoea than someone in the general population," Dr Myles said.
"In the last 10 years or so it has become a lot more well known that people who suffer from schizophrenia suffer from cardiovascular disease and obesity. Another thing we noticed was a lot of our patients lost a significant amount of weight - the average weight loss was about 13kgs.
"We are hoping that the results of our study would lead to more people with schizophrenia being offered sleep studies and the sleep apnoea being diagnosed and treated."
Researchers used CPAP (Continuous Positive Airway Pressure) machines - commonly used for treating sleep apnoea - to measure its effectiveness at treating people with both schizophrenia and severe sleep apnoea.
The positive airway pressure was found to restore normal brain activity during sleep and improved the severity of sleep apnoea. It also improved memory and the overall health of participants.
According to the World Health Organisation schizophrenia affects more than 21 million people worldwide and can cause disruptions in cognitive processing.
Severe sleep apnoea is a disorder where people experience frequent pauses in breath while sleeping. Many people are forced to wake up multiple times during the night to regulate their breathing and ensure sufficient release of carbon dioxide form the body.
University of Adelaide professor Cherrie Galletly said most patients with schizophrenia reported they had experienced difficulty sleeping.
"Despite these illnesses being closely linked with obstructive sleep apnoea, the rates of this disorder and the benefits of treating it in this population are unknown.
"People with obstructive sleep apnoea also have high rates of heart disease, depression and poor memory, so obstructive sleep apnoea may be causing these problems in many people with schizophrenia, but no one is aware of this."
The study titled How long will we sleep on obstructive sleep apnoea in schizophrenia? was published in the Australian and New Zealand Journal of Psychiatry. It was recently presented at the Royal Australian and New Zealand College of Psychiatrists Congress in Hong Kong.
South Australia's capital Adelaide has three long-standing public universities, Flinders University, University of South Australia, and the University of Adelaide, each of which are consistently rated highly in the international higher education rankings.
Article: How long will we sleep on obstructive sleep apnoea in schizophrenia? Hannah Myles et al., Australian and New Zealand Journal of Psychiatry, doi: 10.1177/0004867416662919, published online 16 August 2016.