Getting enough sleep is essential for maintaining optimal health and well-being. A recent study published in the European Heart Journal highlights that sleeping less than 5 hours a night is associated with a 74% raised likelihood of developing peripheral artery disease (PAD) compared with the recommended 7-8 hours.
Leg pain and other symptoms of PAD, which happens when narrowed blood vessels reduce the flow of blood to your limbs, can make it hard to get enough sleep. So can certain sleep disorders that are linked to PAD.
PAD is most often caused by atherosclerosis, which is when fats and other debris from your bloodstream build up inside your arteries. It usually affects the blood supply to your legs, but sometimes it involves your arms.
Both insufficient night-time sleep and excessive daytime napping have been previously linked to an increased risk of coronary artery disease, which, like PAD, results from obstructed arteries.
This study aimed to address the knowledge gap surrounding the impact of sleep habits on PAD and vice versa, providing valuable insights into the relationship between the two. “Our study suggests that sleeping for 7-8 hours a night is a good habit for lowering the risk of PAD,” said study author Dr. Shuai Yuan of the Karolinska Institute, Stockholm, Sweden.
More than 200 million people globally have PAD, where arteries in the legs are clogged, restricting blood flow, and increasing the risk of stroke and heart attack.
Using genetic data to study PAD risk
The study included more than 650,000 participants and was conducted in two stages:
- First, the researchers analysed the associations of sleep duration and daytime napping with the risk of PAD.
- In the second part, the investigators used genetic data to perform naturally randomised controlled trials – called Mendelian randomisation – to examine causality of the associations.
Mendelian randomisation is a research method that uses genetic information to see if there is a cause-and-effect relationship between certain factors and a particular outcome. In simple terms, it is like a natural experiment that takes advantage of the random way our genes are inherited.
This method helps researchers separate true cause-and-effect relationships from mere associations, providing stronger evidence for potential causal links. Mendelian randomisation is a reliable technique for assessing causality, offering greater confidence in the findings.
Link between short sleep duration and PAD
In an observational study involving 53,416 adults, sleeping less than 5 hours a night nearly doubled the risk of PAD compared to sleeping 7-8 hours. Additional analyses with 156,582 and 452, 028 individuals supported this finding.
In the causal studies, not only was short sleep linked to an increased risk of PAD, but having PAD also increased the likelihood of not getting enough sleep.
These results suggest that insufficient night-time sleep can heighten the risk of developing PAD, and having PAD, in turn, can lead to inadequate sleep.
Dr. Yuan said, “Insufficient night-time sleep and daytime napping have previously been associated with a raised risk or coronary artery disease which, like PAD, is caused by clogged arteries. In addition, sleeping problems are among the top ranked complaints in PAD patients. There are limited data on the impact of sleep habits on PAD and vice versa, and our study aimed to fill that gap.”
Link between long sleep duration and PAD
In the case of long sleep, an observational study of 53,416 adults found that sleeping 8 or more hours per night was associated with a 24% increased risk of PAD compared to sleeping 7-8 hours.
This observation was backed by analyses in two larger groups of 156,582 and 452,028 individuals. However, no cause-and-effect relationship was discovered between long sleep and PAD.
The researchers reported similar findings for daytime napping, where those who napped had a 32% higher risk of PAD than non-nappers, but no causal connections were established.
Dr. Yuan said, "Observational analyses are limited by reverse causality—meaning that if an association between sleep habits and PAD is found, we cannot be certain if sleep habits caused PAD or having PAD caused the sleep habits. Mendelian randomisation is a robust method for evaluating causality and provides more certainty about the results."
Taken together, the strongest evidence was for short sleep, where the relationship with PAD went both ways. In an observational analysis of 53,416 adults, sleeping less than five hours a night was associated with a nearly doubled risk of PAD compared with seven to eight hours (hazard ratio [HR] 1.74; 95% confidence interval [CI] 1.31–2.31).
This finding was supported by further analyses in 156,582 and 452,028 individuals. In the causal studies, short sleep was associated with an increased risk of PAD and, in addition, PAD was associated with an increased likelihood of short sleep. Dr. Yuan said, "The results indicate that brief night-time sleep can raise the chance of developing PAD, and that having PAD increases the risk of getting insufficient sleep."
Regarding long sleep, in an observational analysis of 53,416 adults, sleeping eight hours or more per night was linked with a 24% higher risk of PAD compared with seven to eight hours (HR 1.24; 95% CI 1.08–1.43). This finding was supported by analyses in two larger populations of 156,582 and 452,028 individuals.
However, no causal relationships were found between long sleep and PAD. Similar results were reported for napping, where daytime nappers had a 32% higher risk of PAD compared to those who did not nap (HR 1.32; 95% CI 1.18–1.49) but no causal links were found. "More studies are needed on the relationships between lengthy night-time sleep, daytime napping and PAD," said Dr. Yuan. "Although we found associations in the observational studies, we could not confirm causality."
He concluded, "More research is needed on how to interrupt the bidirectional link between short sleep and PAD. Lifestyle changes that help people get more sleep, such as being physically active, may lower the risk of developing PAD. For patients with PAD, optimising pain management could enable them to have a good night's sleep."