It turned out that poor, fragmented sleep leads to an increase in the level of neutrophils (but not monocytes), as well as an increase in calcium deposits on the walls of the coronary arteries. The latter indicator indicates a growing risk of developing atherosclerosis. Statistical calculations have shown that the effect of sleep fragmentation on coronary calcium is mediated precisely by an increase in the number of neutrophils. And this relationship — worse sleep, more neutrophils, more calcium on the walls of the coronary arteries — remained unchanged even after taking into account many other factors that affect the risks of developing cardiovascular diseases.
Thus, the researchers conclude that improved sleep can reduce the extent of inflammatory processes in the body and thereby reduce the threat to the heart and blood vessels.
Interestingly, scientists have also tried asking subjects about the quality of their sleep, and it turned out that the data obtained in this way is subjective and does not always correspond to reality. This suggests that asking people about sleep quality is an unreliable tool for conducting research to assess sleep-related cardiovascular risk.