Coronary artery calcification (CAC) is an established imaging biomarker of subclinical atherosclerosis, but its relationship to diurnal preference needs to be better studied.
The disease develops gradually and may go unnoticed until it results in conditions like angina, blood clots, heart attack, or stroke. Earlier studies have indicated that individuals with late-night habits face an increased risk of cardiovascular disease.
A new study from the University of Gothenburg, Sweden, investigated the association between chronotype and CAC. It found that artery calcification is almost twice as common in night owls compared to early birds. This is the first study to show how circadian rhythm affects explicitly artery calcification.
Involving 771 individuals aged 50 to 64 from the SCAPIS population study, the research assessed the degree of artery calcification in the coronary arteries using computer tomography. Participants self-reported their chronotype on a five-point scale, ranging from extreme morning to extreme evening.
Among extreme morning types, 22.2% had pronounced artery calcification, the lowest proportion among all chronotypes. In contrast, the extreme evening type group exhibited the highest incidence of severe coronary artery calcification, at 40.6%.
The first author of the study is Mio Kobayashi Frisk, a doctoral student at Sahlgrenska Academy, University of Gothenburg said, “Our results indicate that the extreme evening chronotype may be linked not only to poorer cardiovascular health in general but also more specifically to coronary artery calcification and the process that leads to artery calcification.”
The statistical analysis considered factors influencing artery calcification risk, such as blood pressure, blood lipids, weight, physical activity, stress level, sleep, and smoking.
In addition to established risk factors, the individual circadian rhythm is a noteworthy factor influencing artery calcification. The findings suggest that circadian rhythm plays a more substantial role in the early stages of the disease process, emphasizing its importance in the preventive treatment of cardiovascular diseases, particularly.
The study excluded individuals who had suffered a heart attack, resulting in participants being generally healthier than the broader population. Researchers acknowledged weaknesses in the study, including participants self-reporting their chronotype.
Each chronotype has an average time when half of the night’s sleep has passed, with the extreme morning type group having a mid-sleep time of 02:55 AM and the extreme evening type group at 04:25 AM, according to a previous study on a similar population.
Journal Reference:
- Mio Kobayashi Frisk, Erika Fagman et al. Eveningness is associated with coronary artery calcification in a middle-aged Swedish population. Sleep Medicine. DOI: 10.1016/j.sleep.2023.11.004