Measures of Sleep Duration and Quality in Sri Lanka

Abstract

A link between poor sleep and abnormal health outcomes has been established.The majority of this research is conducted in Western, high-income country (HIC) settings which warrants the question of how relevant the findings and the derived consensus statements are to low-middle income countries (LMICs). Sleep duration and quality are known to be affected by cultural, social, environmental and geographical influences which vary significantly between LMIC and their HIC counterparts. This thesis provides a thorough examination of objective and subjective measurements of sleep in a LMIC setting. Objective and subjective measures of sleep were obtained as part of an actigraphic sub-study nested within the Colombo twin and singleton study, a cohort study of twins and singletons randomly selected from Colombo, Sri Lanka. Results comparing actigraphic and self-reported sleep duration indicated that Sri Lankans have short sleep duration; averaging 6.4h (SD 1.5) self-reported and 6.0h (SD 0.9) actigraphically. Poor sleep quality was prevalent with an average WASO of 49 min, and sleep efficiency <85%. Bias was observed, with self-report consistently over-reporting sleep on average by 27.6 min (95% CI: -0.68, -0.24) compared to objective measures, but wide individual variation in disagreement, ranging from overreporting by 3.34h to under-reporting by 2.42h. Agreement between subjective and objective measurements of sleep quality was also assessed. Objective indices of sleep efficiency, sleep onset latency and wake after sleep onset did not agree with each other and were unable to be combined into more useful composite indices as a ‘global’ measure of an individual’s satisfaction with their sleep. Given the high cardiometabolic morbidity in Sri Lanka and poor measurement agreement observed, this warrants further investigation and supports the need for culturally appropriate, reliable, and valid assessment for analytic epidemiology in non-Western settings.