The CAMH-led study, "Accelerometer-derived sleep measures and lifetime psychiatric diagnoses," has just been published in the journalPLOS Medicine．

"The differences in sleep patterns indicated worse sleep quality for participants with a previous diagnosis of mental illness, including waking up more often and for longer periods of time," said senior author Dr. Shreejoy Tripathy, an Independent Scientist at CAMH's Krembil Centre for Neuroinformatics. He also emphasized that gauging the quality of sleep was just as important as measuring the total amount with regard to its impact on mental health.

"The relationship between sleep and mental health is bi-directional," said lead author Dr. Michael Wainberg, a postdoctoral researcher at the Krembil Centre for Neuroinformatics. "Poor sleep contributes to poor mental health and poor mental health contributes to poor sleep. Sleep pattern differences were a feature of all mental illnesses we studied regardless of diagnosis."

The study was based on data collected from 89,205 participants in the United Kingdom who agreed to wear an accelerometer on their wrist that tracked body movement 24 hours a day for seven days. They also consented to having their data stored in a digital biobank for research purposes. The authors used computational algorithms -- including machine learning -- to summarize this vast amount of data into ten metrics, including bedtime, wake time, naps and the longest duration of uninterrupted sleep. They then compared these metrics between participants who had received a previous diagnosis of mental illness in their lifetime and those who had not.

"We know that up to 80 per cent of people with mental health disorders can have problems with falling asleep, staying asleep or waking up earlier than they intended," said CAMH psychiatrist and sleep disorder specialist Dr. Michael Mak. "We know that sleep disturbances cause a great burden to society, including an economic one. And we know that treatments that improve sleep quality, whether it is therapy or some types of medication, can improve mental health outcomes."

This is the first large-scale transdiagnostic study of objectively measured sleep and mental health, and the study's unique methodology allowed for sleep monitoring to be conducted in each individual's natural home sleep environment rather than in a laboratory setting.

"Until now nobody has looked at objectively measured sleep in the context of mental illness at quite this scale before," said Dr. Tripathy. "Part of why we wanted to do this study is that with the emergence of smartphones and wearables, we have access to data streams that we never had before."

The Krembil Centre for Neuroinformatics is currently developing a patient data biobank similar to the one in the UK that was used for this study. The core goal of the CAMH BrainHealth Databank is to use patient data, including the use of wearables outside of a hospital setting, to deliver improved, personalized mental health care in the present, while also accelerating future clinical research, discovery and innovation.