Sleep

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

Yamada T, Yamamoto Y, et al. • Journal of clinical lipidology • 2026

PubMed 41605755 DOI 10.1016/j.jacl.2025.12.020
TL;DR

Poor sleep quality is associated with unfavorable lipid profiles, especially elevated sdLDL-C levels, independent of confounders including sleep duration.

Key Findings

Results

Poor sleepers with less than 6 hours of sleep had significantly higher sdLDL-C levels than good sleepers in both men and women.

  • In men sleeping <6 hours, median sdLDL-C was 34.1 mg/dL in poor sleepers vs 31.7 mg/dL in good sleepers
  • In women sleeping <6 hours, median sdLDL-C was 26.9 mg/dL in poor sleepers vs 24.0 mg/dL in good sleepers
  • Differences were statistically significant in both genders
  • A similar trend was observed in the 6-8-hour sleep duration group
Results

No significant difference in sdLDL-C between poor and good sleepers was found in the group sleeping 8 or more hours.

  • Participants were classified into three groups: <6 hours, 6-8 hours, and ≥8 hours of sleep
  • The association between poor sleep quality and elevated sdLDL-C was not statistically significant in the ≥8-hour group
  • This suggests a potential interaction between sleep duration and sleep quality on sdLDL-C levels
Results

Multivariable log-linear regression confirmed that poor sleep quality was independently associated with higher sdLDL-C levels.

  • The association remained significant after adjustment for confounders
  • Sleep quality was assessed via self-reported questionnaire and categorized as either good or poor
  • The analysis was conducted in a population of 24,984 Japanese men and women who underwent medical checkups between April 2018 and March 2019
Results

Poor sleep quality was associated with unfavorable lipid profiles more broadly, not limited to sdLDL-C alone.

  • Blood samples were used to measure serum lipid profiles including sdLDL-C
  • sdLDL-C was highlighted as a particularly sensitive lipid parameter associated with sleep quality
  • The study population included both men and women, allowing gender-stratified analysis
Methods

The study enrolled 24,984 Japanese men and women using a cross-sectional design with self-reported sleep measures.

  • Participants underwent medical checkups between April 2018 and March 2019
  • Sleep duration and sleep quality data were obtained using self-reported questionnaires
  • Group comparisons and multivariate analyses were both performed to assess sleep-lipid associations
  • The study population was specifically Japanese, which may limit generalizability to other ethnic groups

What This Means

This research suggests that the quality of sleep — not just how long a person sleeps — is linked to higher levels of a particularly harmful type of cholesterol called small dense LDL cholesterol (sdLDL-C). In a large study of nearly 25,000 Japanese adults, people who reported poor sleep quality had noticeably higher sdLDL-C levels compared to those who slept well, and this was true for both men and women. The difference was most pronounced among people who also slept fewer than 6 hours per night, while among those sleeping 8 or more hours, poor sleep quality was not significantly associated with higher sdLDL-C. sdLDL-C is considered a particularly atherogenic (artery-clogging) form of LDL cholesterol that may contribute to cardiovascular disease risk beyond what standard cholesterol tests capture. The finding that poor sleep quality independently raised sdLDL-C levels — even after accounting for other lifestyle and health factors — highlights that sleep quality may be an important but often overlooked factor in heart health. This research suggests that addressing sleep quality could be a meaningful, modifiable lifestyle intervention for improving cholesterol profiles and potentially reducing cardiovascular disease risk. Rather than focusing solely on sleep duration, clinicians and individuals might also benefit from paying attention to sleep quality as part of overall cardiovascular health management.

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Citation

Yamada T, Yamamoto Y, Toragai R, Watanabe Y, Kuroshima T, Arimoto M, et al.. (2026). Association of sleep duration and quality with small dense low-density lipoprotein cholesterol.. Journal of clinical lipidology. https://doi.org/10.1016/j.jacl.2025.12.020