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NEW STUDY: Cardiologist examines impact of sleep disruption on healing heart

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“If you want a good night’s sleep, don’t come to hospital,” said Dr. Michael Sole, lead author of the study, and a cardiologist at the Peter Munk Cardiac Centre in Toronto.
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To improve heart attack recovery, hospitals should make sure natural sleep cycles are not disturbed in the first few days after a heart attack. That's the main finding of a new study on cardiac healing and recovery published in the May 23, 2014 issue of 'Circulation Research.'

"If you want a good night's sleep, don't come to hospital," said Dr. Michael Sole, lead author of the study, and a cardiologist at the Peter Munk Cardiac Centre, University Health Network in Toronto. He defines a natural sleep cycle as approximately seven to eight hours of sleep when it's dark outside and being awake during daytime.

Sole has witnessed the impact of interrupted sleep patterns on patients who are recovering in hospital after a heart attack --- during his 40 years as a cardiologist. It was, in part, the impetus for his study.

Sole's team induced heart attacks in mice and then monitored their recovery. By altering light and dark cycles, the natural sleep patterns of the mice were disturbed for only a few days after the heart attack. This was done to mimic a stay in the Coronary Intensive Care Unit (CICU) of a hospital. The mice were then returned to a normal day and night environment.

The outcomes of the disturbed mice were compared to those that followed a natural sleep cycle after a heart attack. The mice exposed to rhythm disruption showed impaired healing with permanent heart enlargement and worse heart function compared to the mice who maintained a normal, undisturbed day and night schedule.

The healing of a damaged heart requires a specific, orderly sequence of events. Sole likens it to renovating a house.

"If you disrupt day/night rhythms during those critical first few days after your heart attack, then the clearing of debris, the putting up of scaffolding and then rebuilding the walls becomes disordered and you never achieve a tight scar (a proper wound repair). Like a house renovation - events must happen in a precise order, or it won't be done well," he said.

The findings from this study demand similar testing on hospital patients, said Sole. Among potential solutions to make hospitals more sleep-friendly, he suggests simple additions, like the use of blue light-blocking glasses, earplugs low-volume ringtones and greater attention to hospital noise at night. Multi-bedded rooms could yield short-term savings but may come with long-term costs.

"The first thing is awareness," said Sole. "Awareness that what we do in the short-term may have profound adverse effects in the long-term. And that's contrary to what we're trying to accomplish when we treat a patient in hospital."

Dr. Michael Sole is a cardiologist at the Peter Munk Cardiac Centre, University Health Network (UHN) in Toronto, Canada.
To read his study, "Short-Term Disruption of Diurnal Rhythms After Murine Myocardial Infarction Adversely Affects Long-Term Myocardial Structure and Function," click here.​

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