A major study suggests that people who frequently suffer interrupted sleep have an increased chance of heart complications.
The research, which draws on data from more than 14million patients, concluded that those with recurrent night-time awakening have a 26 per cent increased chance of developing an irregular heartbeat. The condition, known as atrial fibrillation, is a major cause of strokes and heart failure.
The research team, from the University of California San Francisco and the University of Michigan, also found that people who suffer insomnia – meaning they struggle to get to sleep at night or did not get enough sleep in total – had a 29 per cent increased risk of atrial fibrillation.
Scientists suspect sleep disruptions put extra stress on the chambers of the heart. This could be because of the way key hormones are regulated during the so-called sleep-wake cycle.
Emerging evidence suggests that sleep affects metabolism and the hormone balance of the body – affecting cholesterol, insulin, blood pressure and inflammation. The part of the brain which regulates heartbeat and blood pressure – the autonomic system – could also be affected by irregular sleep, scientists think.
Doctors had thought cardiovascular health would only be affected at night by sleep apnoea – which causes snoring and dangerous pauses in breathing at night. But the researchers behind the new study took sleep apnoea into account when they calculated their results, and found heart risk remained even among people who did not have the condition.
Lead author Matt Christensen, who analysed the results of three huge datasets with a combined 14million records, said, the idea that these three studies gave us consistent results was exciting. In a separate exercise, he also analysed the sleep quality of 1,131 people by monitoring rapid-eye movement – a key indicator of deep sleep.
Findings showed that having less rapid-eye movement sleep during the night is linked to higher chances of developing atrial fibrillation. Mr Christensen, who presented his findings yesterday at the American Heart Association’s scientific sessions meeting in New Orleans, said, by examining the actual characteristics of sleep, such as how much rapid-eye movement sleep you get, it points us toward a plausible mechanism.
There could be something particular about how sleep impacts the autonomic nervous system.
Co-author Dr Gregory Marcus said, even without a clear understanding of the responsible mechanisms, we believe these findings suggest that strategies to enhance sleep quality, such as incorporating known techniques to improve sleep hygiene, may help prevent this important arrhythmia.
The researchers said getting enough physical activity, avoiding too much caffeine, and having a regular evening routine could all contribute to better sleep.
Earlier this year psychiatrists at the University of Freiburg in Germany found that sleep plays an essential role in resetting the connections of the brain each night. The revelation of this nightly ‘recalibration’ provided a major insight into why slumber is so crucial for different aspects of the way the mind and body works.
It explains why people cope so badly with a lack of sleep, displaying a major decline in cognition after just one night of interrupted snoozing. But scientists are beginning to realise it could also play a role on other organs linked to the brain – including the heart.