Related by context. Frequent words. (Click for all words.) 72 studies 68 Study 67 survey 65 longitudinal study 64 observational study 63 researchers 62 research 62 multicenter study 59 meta analysis 58 randomized controlled trial 57 epidemiological studies 57 epidemiologic studies 56 longitudinal studies 54 Longitudinal Study 54 findings 54 surveys 53 Survey 53 randomized clinical 53 prospective cohort 52 journal Sleep 52 journal Neurology 52 observational studies 51 randomized controlled trials 51 studied 50 Findings 50 Research 50 randomized controlled 50 researches 50 STUDY 50 researcher 50 Ipsos Reid survey 50 analysis 49 Researchers 49 randomized trials 49 Previous studies 48 multicenter 48 randomized clinical trials 48 analyzed 48 randomized placebo controlled 48 journal Circulation 47 journal Pediatrics 47 report 47 placebo controlled 47 postmenopausal women 47 journal Psychological Science 47 journal PLoS ONE 47 journal Biology Letters 47 Health Initiative WHI 46 randomized 46 Sterility 46 clinical trial 46 American Geriatrics Society 46 meta analyzes 46 Studies 46 surveyed 45 statistical analysis 45 Lancet Oncology 45 journal Lancet 45 Sahlgrenska Academy 45 analyzes 45 Surveys 45 laboratory experiments 44 General Psychiatry 44 biostatistician 44 peer reviewed 44 NHANES 44 feasibility study 44 experiment 44 RCTs 44 prospective randomized 44 Nutrition Examination Survey 44 journal Annals 44 WHI 44 journal PLoS 44 journal Archives 44 Lancet 43 experiments 43 Annals 43 randomized double 43 journal Nature Neuroscience 43 Epidemiology 43 premenopausal women 43 post menopausal 43 Clinical Nutrition 43 Researches 43 cohort 43 authors conclude 43 epidemiological 43 journal Science 43 Interview Survey 43 blind randomized 43 journal Nature Geoscience 43 accompanying editorial 43 Karolinska Institute 42 random sample 42 & Rheumatism 42 National Institutes 42 double blind placebo 42 postmenopausal 42 brain scans 42 Experimental Research