TABLE 1.
Summary of epidemiologic studies evaluating the relations between dairy intake and sleep quality
| First author, year | Study population | Study design | Dairy exposure | Sleep outcome | Relevant findings |
|---|---|---|---|---|---|
| Knowlden et al., 2015 [21] | 270 US students aged 18 y or older, M and F | Cross-sectional | Self-reported servings of dairy product per day based on FFQ: 1. Healthy dairy (milk, cottage cheese, yogurt) 2. Unhealthy dairy (cheese, processed cheese) |
Sleep quality: poor (PSQI scores ≥5) or good (PSQI scores <5) | 1. Healthy dairy: higher frequency of consumption related to lower odds of poor sleep 2. No association of unhealthy dairy intake with sleep quality |
| Hepsomali and Groeger, 2021 [22] | 500,000 UK adults (from UK Biobank), 40–69 y, M and F | Cross-sectional | Milk intake scores, determined from estimated total milk intake per day based on FFQ: low, low/medium, medium, medium/high, high | Composite sleep score (range: 0–5), with higher scores representing better sleep | Curvilinear relationship between milk intake score and sleep score |
| Sleep quality was lowest for high and low milk intake scores | |||||
| Yasuda et al., 2019 [23] | 679 Japanese elite athletes mean age: 25 y (range not provided), M and F | Cross-sectional | Self-reported servings of dairy intake based on frequency of consuming: 1. Milk + other dairy 2. Milk 3. Other dairy All exposures grouped as follows: low (0–2 d/wk), moderate (3–5 d/wk), high (6–7 d/wk) |
Sleep quality: good or normal/poor | 1. Milk + other dairy: not associated with sleep 2. Milk: moderate and high frequency of consumption related to lower odds of poor sleep among women only 3. Other dairy: moderate and high frequency of consumption tended to relate to lower odds of poor sleep across all subjects and in men |
| Kitano et al., 2014 [24] | 421 Japanese adults aged 65 y or older, M and F | Cross-sectional | Frequency and quantity of dairy consumed using self-reported questionnaire: 1. Milk 2. Yogurt 3. Cheese 4. Total dairy Each intake exposure grouped as none, low, and high Physical activity: engaging or not engaging |
DIS from PSQI sleep onset latency: no-DIS (≤30 min) or DIS (>30 min) | 1. a) High level of milk intake related to lower odds for DIS b) Engaging in PA + consuming milk related to lower odds for DIS 2. a) Yogurt intake was not associated with DIS 3. a) Cheese intake was not associated with DIS b) Engaging in PA + consuming cheese related to lower odds for DIS 4. a) Total dairy was not associated with DIS |
| van Egmond et al., 2019 [25] | 970 Swedish older adults (from Uppsala Longitudinal Study of Adult Men), aged 70 y or older, M only | Cross-sectional | Amount consumed of milk and dairy products per day using self-report: low (<median intake) or high (≥median intake) | DIS: Yes or no | Low milk and dairy intake related to lower odds for DIS |
| DMS: Yes or no | No association of milk and dairy intake with DMS |
DIS, difficulty initiating sleep; DMS, difficulty maintaining sleep; F, female; FFQ, food frequency questionnaire; M, male; PSQI, Pittsburgh Sleep Quality Index.