| Aim: Depression is a common psychiatric disorder,marked by high incidence and recurrence rate,high suicide rate,and increased morbidity.In China,about 40% of elderly aged ≥60 years had reported depressive symptoms.Prior research abroad has investigated the association between nighttime sleep duration and depression,and the results in the literature are inconsistent.In addition,most of studies are cross-sectional design,the findings of cross-sectional studies give little information about the direction of causality.To date,there is a paucity of information regarding the longitudinal relationship between nighttime sleep duration and risk for incidence /remission depression,and the impact of midday napping on depression has not been explored in-depth.This study is based on a nationally representative survey on community-based population aged 45 years or older,to investigate whether nighttime sleep duration and midday napping were independently associated with incidence and persistence of depressive symptoms,for elderly depression prevention and provide scientific basis for intervention and treatment strategies.Methods: Data from “China Health and Retirement Longitudinal Study”,CHARLS(2011-2015),were analyzed.A total of 17,708 individuals agreed to participate in the baseline(wave 1,W1)survey from 2011 to 2012.The fourth wave(wave 4,W4)survey successfully re-interviewed 13,842 people among them from 2015 to 2016.Nighttime sleep duration was categorized as < 6 hours,6-7 hours,7-8 hours and > 8 hours and 7-8 hours were chosen as the referent categories.Midday napping was classed as none,< 60 minutes and ≥ 60 minutes.Lack of midday napping was chosen as the reference.Depressive symptoms were identified by the 10-item version of the Epidemiological Studies Depression scale(CESD-10).A total score of ≥ 10 was defined as clinically significant depressive symptoms.Among individuals with total CESD-10 score < 10 at W1,those who were subsequently diagnosed as having depression by a medical doctor or who endorsed the CESD-10 scores ≥ 10 at W4 were grouped as incidence of depressive symptoms,and the rest were grouped as non-depressive symptoms.Among individuals with CESD-10 scores ≥ 10 at W1,those who were taking anti-depressant medicine or CESD-10 scores ≥ 10 at W4 were grouped as persistent depressive symptoms,and the rest were grouped as reversion of depressive symptoms.we used the relative risk(RR),attributable risk percent(AR%),population attributable risk percent(PAR %)to reflect sleep as risk factor for developing incidence and persistence of depressive symptoms.The dependent variable was presented according to depressive status(depression = 1,normal = 0),binary logistic regression models was used to estimate the independent effect of baseline nighttime sleep duration and midday napping on incidence and persistence of depressive symptoms and calculate the odd ratios(ORs)with 95% confidence intervals(CI),the adjusted covariates were: age,marital status,education,drinking status,smoking status,BMI,social activity.Results: A total of 6,970 participants(3,759 males and 3,206 females)with CESD-10 scores < 10 were classified as free of depressive symptoms at baseline,the average age was 57.65±8.67 years,during the follow-up period,the cumulative incident of depressive symptoms was 22.0%.1.The numbers of participants with sleep duration of < 6h,6-7 h,7-8 h,> 8h were 1,373(19.8%),1,576(22.7%),3,390(48.8%)and 609(8.8%),respectively.The incident of depressive symptoms in participants with < 6h,6-7 h,7-8 h,> 8h were 28.48%,21.07%,19.65%,22.82%.Compared to 7-8 hours,the relative risk(RR)and 95% confidence intervals(CI)of nighttime sleep duration < 6 h,6-7 h,7-8 h,>8 h for incident depressive symptoms were 1.45(1.30,1.61),1.07(0.95,1.21),1.16(0.99,1.36).Compared with reference sleep duration,the fully adjusted ORs(95% CI)of nighttime sleep duration <6 h,6-7 h,7-8 h,>8 h for incident depressive symptoms were 1.556(1.321,1.831),1.122(0.952,1.324),1.115(0.884,1.407).In female,not only the < 6 h sleep time,6-7 h is also associated with incident depressive symptoms 1.378(1.106,1.106).2.The numbers of participants with midday napping of 0,< 60 min,≥ 60 min were 3,070(44.1%),1,286(18.5%),2,605(37.4%),respectively.The incident of depressive symptoms in participants with 0,< 60 min,≥ 60 min were 23.0%,21.5%,21.0%.Compared to reference midday napping,the relative risk(RR)and 95% confidence intervals(CI)of midday napping 0,< 60 min,≥ 60 min for incident depressive symptoms were 0.94(0.83,1.06),0.91(0.83,1.00).Compared with reference sleep duration,the fully adjusted ORs(95% CI)of midday napping 0,< 60 min,≥ 60 min for incident depressive symptoms were 0.940(0.787,1.123),0.971(0.842,1.119).There were 3,845(1,518 males and 2,324 females)participants with the CESD-10 scores ≥10 at baseline,the average age was 58.81±8.70 years,of these,43.1% had reversion of depressive symptoms while the rest had persistent.3.The numbers of participants with sleep duration of < 6 h,6-7 h,7-8 h,> 8 h were 1,691(44.3%),747(19.4%),1,139(29.6%),243(6.3%),respectively.The incidences of depressive symptoms in participants with < 6 h,6-7 h,7-8 h,> 8 h were 62.6%,52.7%,52.1%,51.9%.Compared to 7-8 hours,the relative risk(RR)and 95% confidence intervals(CI)of nighttime sleep duration < 6 h,6-7 h,7-8 h,> 8 h for incident depressive symptoms were 1.20(1.12,1.28),1.01(0.93,1.11),1.00(0.87,1.14).Compared with reference sleep duration,the fully adjusted ORs(95% CI)of nighttime sleep duration <6 h,6-7 h,7-8 h,>8 h for incident depressive symptoms were 1.507(1.272,1.784),1.033(0.842,1.267),0.956(0.703,1.300).4.The numbers of participants with midday napping of 0,< 60 min,≥ 60 min were 1,996(51.9%),640(16.6%),1,202(31.3%),respectively.The incidences of depressive symptoms in participants with 0,< 60 min,≥60 min were 58.5%,55.0%,55.2%.Compared to reference midday napping,the relative risk(RR)and 95% confidence intervals(CI)of midday napping 0,< 60 min,≥ 60 min for incident depressive symptoms were 0.94(0.87,1.02),0.94(0.89,1.01).Compared with reference sleep duration,the fully adjusted ORs(95% CI)of midday napping 0,< 60 min,≥ 60 min for incident depressive symptoms were 0.844(0.692,1.030),0.912(0.775,1.072).Conclusions: Our study concluded that short nighttime sleep duration was an independent risk factor of incident and persistent depressive symptoms.Reasonable arrangement of sleep time can effectively prevent or relieve depressive symptoms. |
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