Associations between rice, noodle, and bread intake and sleep quality in Japanese men and women.
Level 4 - case-series / case-control
Cross-sectional observational survey
PubMed 25127476 · doi:10.1371/journal.pone.0105198
What was done
This cross-sectional study evaluated 1,848 Japanese men and women aged 20 to 60 years. Dietary intake of rice, bread, noodles, and overall dietary glycemic index were assessed using a self-administered diet history questionnaire. Sleep quality was evaluated via the Japanese version of the Pittsburgh Sleep Quality Index (PSQI), defining poor sleep as a global score greater than 5.5. Multivariate-adjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated across intake quintiles.
What was found
Higher rice intake was associated with significantly reduced odds of poor sleep across increasing quintiles compared to the lowest quintile: OR 0.68 (95% CI: 0.49–0.93), 0.61 (0.43–0.85), 0.59 (0.42–0.85), and 0.54 (0.37–0.81; p for trend = 0.015). Conversely, higher noodle consumption was associated with increased odds of poor sleep across quintiles: OR 1.25 (0.90–1.74), 1.05 (0.75–1.47), 1.31 (0.94–1.82), and 1.82 (1.31–2.51; p for trend = 0.002). Bread consumption showed no significant association with sleep quality. A higher overall dietary glycemic index was significantly associated with a lower risk of poor sleep (p for trend = 0.020).
Why it matters
The study shows that different carbohydrate sources relate differently to subjective sleep quality, with high-glycemic staple foods like rice associating with better sleep outcomes compared to noodles.
Limits
The cross-sectional design cannot establish causality or directionality. Both diet and sleep metrics relied entirely on self-administered questionnaires rather than objective measurements such as actigraphy or polysomnography. Unmeasured confounding from lifestyle, meal timing, or general diet quality may be present, and the results from a Japanese cohort may not generalize to other populations.
Cited by
- supports Scientific research shows that dietary intake of starches improves sleep.