Sleep patterns affect cardiovascular risk regardless of genetics

Getting a good night's sleep can reduce the risk of having a heart attack or stroke, even in people who have a higher genetic predisposition for these diseases, according to a new study. 

Researchers in China and the USA followed 385,000 healthy middle-aged adults over an average period of 8.5 years, and found that participants with good sleeping habits had approximately a 35 percent reduced risk of experiencing a stroke or heart disease. 

'We found that a high genetic risk could be partly offset by a healthy sleep pattern. In addition, we found that people with a low genetic risk could lose this inherent protection if they had a poor sleep pattern' said lead author, Dr Lu Qi from Tulane University in New Orleans, Louisiana.

Participants were each assigned a sleep score of 0-5 based on self-reported sleep patterns. This score was dependent on factors including how many hours the individual slept each night (with 7-8 being optimal) and how often they experienced insomnia and daytime sleepiness, among others.

As part of the UK BioBank project, DNA from each participant was collected and sequenced, and individuals allocated a genetic risk score based on previously known associations between certain genetic signatures and increased risk of cardiovascular disease. 

Among participants with a low genetic risk of cardiovascular disease, those with an unhealthy sleep pattern had a 1.7-fold greater risk of heart disease and a 1.6-fold greater risk of stroke compared to those with a healthy sleep pattern. 

Those with unhealthy sleep patterns and a high genetic risk had a 2.5-fold greater risk of heart disease and a 1.5-fold greater risk of stroke, compared to people with a healthy sleep pattern and a low genetic risk.

However, a healthy sleep pattern was able to compensate for some of the effects of a high genetic risk, with the risk of heart disease being reduced to 2.1-fold, and stroke 1.3-fold.

Dr Qi cautioned that these findings indicate 'an association, not a causal relation.'  

Professor Stephen MacMahon, Principal Director at The George Institute for Global Health, Australia, who was not involved with the study said: 

'In previous studies it was difficult to disentangle risks associated with poor sleep from risks associated with other causes of cardiovascular disease, and this is also the case here. People with poor sleep quality were more likely to have diabetes, hypertension and a range of other risk factors including obesity, which reduces the quality of sleep through snoring and sleep apnoea as well as increasing cardiovascular disease risks.'