Health Notes

The body’s circadian clock plays a critical role in regulating metabolism, and disruption of natural rhythms has been associated with high cholesterol levels and other signs of poor metabolic health.¹ Shift work and other causes of short night-time sleep, as well as variability in sleep and activity patterns from day to day, have been found to correlate with higher cholesterol levels.^{2, 3} Observational evidence indicates those with a preference for evening activity, including eating, have worse metabolic health, including higher cholesterol levels.^{4, 5, 6}

Compared with those who routinely skip breakfast, habitual breakfast eaters have been noted to have better lipid profiles and lower cardiovascular risk.⁷ In a crossover-design clinical trial, 12 healthy participants ate a controlled diet comprised of three meals and two snacks during two eight-week phases: in the first phase, eating was restricted to the hours of 8AM–7PM, but in the second phase, eating was delayed until noon and ended at 11PM. A number of other metabolic markers, including total cholesterol levels, improved after the daytime eating phase and worsened during the delayed eating phase of the trial.⁸ In addition, a habit of eating smaller amounts more frequently during the day has been associated with lower cholesterol levels.⁹

Exercise and a physically active lifestyle have been found in multiple randomised controlled trials to increase protective HDL-cholesterol while decreasing heart disease-related triglyceride, LDL-cholesterol, and total cholesterol levels.^{10, 11} Even low-intensity exercise such as walking and Tai Chi can raise HDL-cholesterol levels, while more rigorous exercise may be needed to lower LDL-cholesterol levels.^{12, 13, 14} Importantly, weight gain appears to nullify the positive effects of exercise on lipid levels.¹⁵ Some evidence suggests evening exercise is more effective than morning exercise for improving cholesterol levels.¹⁶ Physical activity has the additional advantage of lowering risks of heart disease, type 2 diabetes, depression, anxiety, cancer, and myriad other chronic conditions.¹⁷

Smoking impairs lipid metabolism and is linked to increased total, LDL-, and non-HDL-cholesterol levels, as well as lower HDL-cholesterol levels. Even secondhand smoke exposure has negative impacts on cholesterol levels, especially in children.¹⁸ Furthermore, smoking is a major contributor to heart disease. Giving up smoking can result in improvement in lipid levels and is an important strategy for decreasing cardiovascular risk in people with high cholesterol levels.¹⁹

Psychological factors such as anxiety, depression, distress, anger, and hostility have been shown to contribute to heart disease risk in both men and women.²⁰ On the other hand, optimism, conscientiousness, openness to experience, and curiosity have been found to reduce cardiovascular risk.²¹ Some, but not all, research indicates yoga and mindfulness may improve markers of cardiovascular health, including cholesterol levels.^{22, 23, 24}