Table 2.

Characteristics of studies on sleep patterns and prostate cancer risk

Author, countryStudy design, populationNumber of prostate cancerData collectionAdjusted covariablesExposure definitionRisk estimate (95% CI)
Sigurdardottir et al. (2013), IcelandAGES-Reykjavik prospective cohort study135 casesSelf-administered questionnaireAge at study entry, family history of PCA, visit to doctor during previous 12 months, injury or health check-up, level of education, smoking status, alcohol use, diagnosis of benign prostate disease, BMIQ1: Taking medication for sleepHR = 1.70 (1.0–2.9)
Q2: Difficulty falling asleep within 30 minutesHR = 2.2 (1.2–3.9)
Q3: Waking up during the night and having difficulty falling back asleep
Q4: Waking up early in the morning and having difficulty falling back asleep
Severe sleep problem= Q1+Q2+Q3
Very severe sleep problem= Q1+Q2+Q3+Q4
Gaptsur et al. (2014), United StatesCancer Prevention Study–II cohort American Cancer Society volunteers friends, neighbors, and relatives4,974 casesSelf-administered questionnaireAge, race, education, BMI, smoking history, family history of prostate cancer, and frequent or painful urination3–5 hours per night 6 hours per nightRR = 1.64 (1.06–2.54) RR=1.28 (0.98–1.67)
Markt et al. (2015a), United StatesHealth Professional Follow-up Study (HPFS)4,261 casesSelf-administered questionnaireAge, race, vigorous activity level, smoking, diabetes, family history of PCA, snoring status, multivitamin use, energy intake, history of PSA testing, beta-blocker use, marital status, coffee intake, alcohol intake, number of urination per night≥ 10 hours per night Never feeling rested when wake upRR = 0.70 (0.50–0.99) RR = 3.05 (1.15–8.10)
Markt et al. (2015b), SwedenNational Cohort785 casesSelf-administered questionnaireAge, BMI, employment status, snoring, smoking, alcohol use, depressive symptoms, physical activity, coffee intake, multivitamin use, diabetesPoor restorative power of sleepHR = 1.23 (0.93–1.62)
Dickerman et al. (2016), FinlandProspective cohort study of Finnish same-sex twin pairs602 casesMailed questionnaireAge, education, BMI, physical activity, social class, social class, smoking status, alcohol use, snoring, zygosity, chronotype8 hours per nightHR = 0.90 (0.70–1.20)
Fairly poor/poor quality of sleepHR = 1.00 (0.7–1.3)

Abbreviations: BMI, body mass index; PCA, prostate cancer.