Cardiovascular events: combined impact of sleep, exercise and diet

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Cardiovascular-related deaths are the most common global cause of mortality, but modifiable lifestyle factors such as diet, physical activity, exposure to nicotine, improved sleep, and blood pressure have an important role.

Much research has assessed the impact of altering these individual factors, but it fails to account for factor interactions. For example, insufficient sleep serves as a metabolic stressor, increasing the drive to eat more. Some evidence suggests that the incidence of obesity is increased by 38% among those with short sleep duration (less than 5 or 6 hours per night) compared to those with normal sleep duration.

In contrast, interactions among other factors can be additive and beneficial, with one meta-analysis finding that increased physical activity improved sleep. Nevertheless, in general, the interaction between lifestyle factors is often negative.

So, while physical activity can improve sleep quality, the converse is true: a lack of sleep reduces physical activity due to tiredness. Additionally, a lower diet quality negatively affects sleep and the energy levels needed for physical activity.

Understanding the importance of undertaking a multifactorial approach to improving cardiovascular health, therefore, appears to be the best approach. But the extent to which different lifestyle factors need to be changed, and the optimal combination of these factors for better cardiovascular health, remains uncertain.

Fortunately, a recent study sought to determine the minimum and ideal combinations of three lifestyle factors – sleep, diet and physical activity – required for meaningful improvements in cardiovascular health.

Unlocking the combination

Using UK Biobank data, researchers from the University of Sydney followed over 53,000 adults for 8 years. Sleep duration and levels of physical activity were obtained from wrist accelerometer data, and individuals wore these devices for seven consecutive days.

Dietary information was obtained from a food frequency questionnaire. Using this information, the researchers calculated a dietary quality score (DQS) with higher scores indicating a healthier diet.

Using all this data, the team created a Sleep, Physical Activity and Nutrition (SPAN) score that was either low (poor), medium or high (good). The outcome of interest was a Major Adverse Cardiovascular Event (MACE), which included myocardial infarction, stroke and heart failure.

The optimal SPAN combination was approximately 8-9.5 hours of sleep per night, 40-105 minutes of moderate to vigorous physical activity per day, and a DQS score of 33-50. Where individuals achieved this combination, it was associated with a 57% lower risk of MACE.

But equally interesting was the finding that even small changes in these three factors had a noticeable effect on MACE. For example, sleeping for only 11 more minutes, doing an additional 4.5 minutes of moderate-to-vigorous daily physical activity such as climbing stairs or brisk walking, and eating an additional quarter of a cup of vegetables, were associated with a 10% reduction in MACE.

However, the study was observational and therefore subject to several limitations. Firstly, observational studies cannot demonstrate a causal relationship (i.e. that changing sleep, diet and physical activity lowers the risk of MACE).

Secondly, dietary intake was self-reported, which is subject to recall bias. Thirdly, there is always the problem of reverse causation in observational studies. For example, while exercise is often believed to improve health, it is possible that health status influences the level of exercise.

Implications for practice

Notwithstanding the above limitations, how can pharmacy teams best make use of these findings? The Healthy Living Pharmacy framework helps deliver consistent health promotion interventions through community pharmacies.

While these health promotion activities are often effective, some patients may find it challenging to follow the recommendations.

The current research suggests that, even when patients struggle to achieve their desired targets, recommending small, incremental steps towards them is beneficial. But perhaps most importantly, it has highlighted the importance of a multi-factorial health promotion approach to improve cardiovascular health outcomes.