Sleeping for seven or more hours a night may reduce the risk of morbidity and mortality from cardiovascular disease (CVD), a Dutch study has found. Getting sufficient sleep and adherence to four traditional healthy lifestyle factors were all associated with a fall in risk. When sufficient sleep was added to these factors, the risk of CVD was further reduced.

The Monitoring Project on Risk Factors for Chronic Diseases (MORGEN) looked at how adequate sleep might enhance the cardiovascular benefits of more traditional healthy behaviours.

This prospective study analysed data from 8,128 men and 9,759 women aged 20-65 years, living in the Netherlands, who replied to a lifestyle questionnaire in 1994 to 1997. All the participants in the study were free of CVD at baseline. The authors defined four traditional healthy lifestyle habits, as follows:

• At least 3.5 hours/week cycling or doing other sports at a moderate to vigorous intensity

• Modified Mediterranean diet score ≥ 5

• Moderate drinking ( ≥ 1 drink of alcohol a month)

• Not smoking

To this list they added another, non-traditional, healthy behaviour: sleeping seven hours or more a night.

Cardiovascular morbidity and mortality were ascertained through national registers. Hazard ratios (HR) were adjusted for age, sex, and educational level. At baseline 6% adhered to one or fewer of the five healthy behaviours and 12% to all five. The follow-up period was 10-14 years.

There were 607 composite CVD events: 129 fatal CVD events, 367 non-fatal myocardial infarctions, and 111 non-fatal strokes.

Those participants who had four traditional healthy lifestyle factors had a 57% lower risk of composite CVD,

HR 0.43 (95% CI:0.31-0.59) and a 67% lower risk of fatal CVD, HR 0.33 (95% CI:0.16-0.68) compared with those with none or one healthy lifestyle factor.

Sufficient sleep in addition to the four traditional lifestyle factors resulted in a 65% lower risk of composite CVD, HR 0.35 (95% CI:0.23-0.52), and an 83% lower risk of fatal CVD, HR 0.17 (95% CI:0.07-0.43).

Each healthy behaviour alone reduced the risk of CVD: ranging from a 12% lower risk with a healthy diet to a 43% lower risk for not smoking.

The risk of fatal CVD ranged from 26% lower for being physically active to 43% lower for not smoking.

Having sufficient sleep reduced the risk of CVD by 22% (HR 0.78) and fatal CVD by 43% (HR 0.57) compared with having insufficient sleep.

The authors postulate that insufficient sleep has an adverse impact on blood pressure and body mass index which could explain the findings. This data provides a strong argument for a new health message to give to our patients: try to go to bed a little earlier!

Dr Peter Savill