Association of sleep duration and quality with small dense low-density lipoprotein cholesterol

BACKGROUND: Although the association between sleep duration and lipid profiles and/or cardiovascular disease has been extensively studied, evidence regarding sleep quality remains limited. OBJECTIVE: This study aimed to investigate the association of sleep duration and quality with lipid parameters, including serum concentration of small dense low-density lipoprotein cholesterol (sdLDL-C) in a Japanese population. METHODS: A total of 24,984 Japanese men and women who had a medical checkup between April 2018 and March 2019 were included in this study. Data on sleep duration and sleep quality were obtained using self-reported questionnaires. Participants were classified into 3 groups based on sleep duration (<6 hours, 6-8 hours, and ≥8 hours). Sleep quality was categorized as either good or poor. Blood samples were used to measure serum lipid profiles, including sdLDL-C. Group comparison and multivariate analyses were performed to assess the association between sleep and these lipid parameters. RESULTS: In the <6-hour group, poor sleepers had significantly higher serum levels of median sdLDL-C than good sleepers in both genders (34.1 vs 31.7 mg/dL in men, 26.9 vs 24.0 mg/dL in women, respectively). A similar trend was observed in the 6-8-hour group, whereas no significant difference was found in the ≥8-hour group. Multivariable log-linear regression showed that poor sleep quality was associated with higher sdLDL-C levels independent of confounders. CONCLUSION: Poor sleep quality is associated with unfavorable lipid profiles, especially elevated sdLDL-C levels. Recognizing sleep quality as a modifiable lifestyle factor could contribute to reducing lipid abnormalities and preventing cardiovascular disease.