Key Features of the Study

• 385,292 healthy participants from the UK Biobank Project were included in the prospective study
• All patients suffering from CVD were excluded from the study
• The following factors that could influence the results were taken into account while designing the study:
• Age
• Sex
• Ethnicity
• Physical activity
• Body mass index (BMI)
• Smoking
• Alcohol consumption
• Sleep deprivation
• Family history of heart disease and stroke
• Other health problems
• Genetic variations called SNPs (single nucleotide polymorphisms) linked to the development of CVD were studied
• SNPs from blood samples of the participants were analyzed
• Genetic Risk Score was developed based on the SNP analysis, which categorized participants into the following:
• High risk of developing CVD
• Intermediate risk of developing CVD
• Low risk of developing CVD
• Healthy Sleep Score (HSS) was developed based on the following parameters of the participants:
• Morning or evening person
• Duration of sleep
• Presence of insomnia
• Presence of snoring
• Excessive daytime sleepiness
• HSS ranged from 0 to 5, which exhibited the following features:
• HSS 5: Healthiest sleep pattern - Persons had 7-8 hours sound sleep at night, without snoring, insomnia or daytime sleepiness
• HSS 0: Least healthiest sleep pattern - Persons experienced disturbed sleep
• Average follow-up period was 8.5 years

Key Findings of the Study

• 7,280 cases of heart disease and stroke occurred during the follow-up period

Participants with HSS 5 compared to HSS 0-1 exhibited the following:

• 35 percent reduced risk of CVD
• 34 percent reduced risk of both heart disease and stroke
• 7 fewer cases of CVD per 1000 people annually

Effects of the following parameters on CVD were studied:

• Group 1: High Genetic Risk + Unhealthy Sleep Pattern
• Group 2: Low Genetic Risk + Healthy Sleep Pattern
• Group 3: High Genetic Risk + Healthy Sleep Pattern
• Group 4: Low Genetic Risk + Unhealthy Sleep Pattern

Results are indicated below:

• Group 1 exhibited 2.5 fold higher risk of heart disease than Group 2
• Group 1 exhibited 1.5 fold higher risk of stroke than Group 2
• Group 3 exhibited 2.1 fold higher risk of heart disease than Group 2
• Group 3 exhibited 1.3 fold higher risk of stroke than Group 2
• Group 4 exhibited 1.7 fold higher risk of heart disease than Group 2
• Group 4 exhibited 1.6 fold higher risk of stroke than Group 2

Interpretation of the Results

The findings indicate the following:

• Among high genetic risk + unhealthy sleep pattern groups, there were 11 more cases of heart disease and 5 more cases of stroke per 1000 people annually, compared to low genetic risk + healthy sleep pattern groups
• Healthy sleep pattern slightly compensated for high genetic risk, with just over 2 fold higher risk of CVD in this group of participants

"We found that a high genetic risk could be partly offset by a healthy sleep pattern," said Qi. "In addition, we found that people with low genetic risk could lose this inherent protection if they had a poor sleep pattern."

Limitations of the Study

Some of the major limitations of the study included the following:

• Unhealthy sleep pattern could be indicative of an underlying or undetected health condition that increased the risk of CVD
• Sleep patterns were assessed based on self-reporting by the participants only once at the start of the study
• HSS did not include all sleep-related problems, including restless leg syndrome
• Majority of the participants were of European origin, making it difficult to generalize the findings to other populations

Concluding Remarks

The research team couldn't find the exact mechanism that could explain the link between sleep patterns and CVD risk. They opined that altered sleep patterns could disrupt the body's hormonal or metabolic pathways and circadian rhythm, as well as increase inflammatory and 'fight or flight' responses, which could influence CVD risk.

Qi concluded: "As with other findings from observational studies, our results indicate an association, not a causal relation. However, these findings may motivate other investigations and at least suggest that it is essential to consider overall sleep behaviors when considering a person's risk of heart disease or stroke."

Funding Source

The study was funded by the NIH/National Heart, Lung, and Blood Institute and the NIH/National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA.

References :

1. Sleep Patterns, Genetic Susceptibility, and Incident Cardiovascular Disease: A Prospective Study of 385,292 UK Biobank Participants - (https://doi.org/10.1093/eurheartj/ehz849)
2. Can Good Sleep Patterns Offset Genetic Susceptibility to Heart Disease and Stroke? - (https://www.escardio.org/The-ESC/Press-Office/Press-releases/Can-good-sleep-patterns-offset-genetic-susceptibility-to-heart-disease-and-stroke)

Source: Medindia