Abstract
BACKGROUND: Not having social support has been associated with poor sleep, but most prospective studies were based on social support in the workplace, did not account for baseline sleep characteristics or did not assess sleep duration. Moreover, no previous research has evaluated the relationship between social network and sleep outcomes in an older Spanish population. METHODS: 1444 individuals aged ≥60 years were followed between 2012 and 2015. At baseline (2012), a poor social network index (SNI) was computed by summing the following dichotomous indicators: not being married; living alone; not having daily contact with family, friends or neighbors; being alone ≥8h/day; lacking someone to go for a walk with; not having emotional support; lacking instrumental support. Higher values in SNI indicate less social support. In 2012 and 2015, information was collected on sleep duration (hours/day) and on symptoms of sleep disturbance: bad overall sleep; difficulty falling asleep, awakening during nighttime, early awakening with difficulty getting back to sleep, use of sleeping pills, feeling restless in the morning, being asleep at daytime, and having an Epworth Sleepiness Scale>10. Poor sleep duration was defined as short (<6 h) or long (>9 h) nighttime sleep, and poor sleep quality as having ≥4 indicators of sleep disturbance. Linear or logistic regression models were used to assess the relationship of SNI with changes in sleep duration and in number of sleep disturbance indicators, or with the risk of developing poor nighttime sleep or poor sleep quality. RESULTS: Compared to individuals in the lowest (best) quartile of the SNI in 2012, those in the second, third and fourth quartiles, respectively, displayed a mean (95%confidence interval [95% CI]) change of 2.32 (-7.58-12.22), -2.70 (-13.19-7.79) and -13.04 (-23.41- -2.67) minutes in sleep duration from 2012 to 2015; p for trend=0.02. A 1-point increase in the SNI at baseline was associated with an increased risk of short nighttime sleep (Odds Ratio [OR] and 95% CI: 1.22 (1.05-1.42)), poor sleep quality (OR: 1.13; 95% CI: 1.00-1.30), and of the indicator of sleep disturbance "early awakening with difficulty getting back to sleep" (OR: 1.20; 95% CI: 1.07-1.35). CONCLUSION: A poorer social network is associated with a higher risk of short sleep and poor sleep quality in older adults.