Relationships among Sleep, Circadian Rhythms, Social Timing and Symptoms in Adults Living with a Health Condition

Abstract

The overall purpose of this dissertation was to examine the relationships among sleep, circadian rhythms, social timing and symptoms in adults living with a health condition and in particular adults with acute respiratory failure (ARF) and irritable bowel syndrome (IBS). Manuscript one examined diary and actigraphic sleep variables as well as actigraphic rest-activity circadian rhythms in ARF survivors three months after hospital discharge, and to compared them with a community-dwelling population. Sleep diary, actigraphy data, and insomnia symptoms were collected in a pilot study of 14 ARF survivors. Rest-activity circadian rhythms were assessed with wrist actigraphy and sleep diary for nine days, and were analyzed by cosinor and nonparametric circadian rhythm analysis. The results showed that all ARF participants had remarkable actigraphic sleep fragmentation, 71.5% had subclinical or clinical insomnia symptoms. Compared to community-dwelling adults, this cohort had less stable rest-activity circadian rhythms (p<0.001), and weaker circadian strength (p<0.001). The pilot study showed insomnia and circadian disruption were common in ARF survivors. As such, sleep improvement and circadian rhythm regularity may be a promising approach to improve quality of life and daytime function after ARF. Manuscript two examined potential indirect effects of sleep on abdominal pain symptoms simultaneously through psychological distress and daytime dysfunction in adults with IBS. Daily symptoms of nighttime sleep complaints (poor sleep quality and unrefreshed sleep ), psychological distress, daytime dysfunction (fatigue, sleepiness, and hard to concentrate) and abdominal pain were collected in baseline assessments from two randomized controlled trials of 332 adults (mean age 42 years and 85 % female) with IBS. Structural equation modeling (SEM) was used to examine the global relationships among nighttime sleep complaints, psychological distress, daytime dysfunction and abdominal pain. SEM analyses suggest that the primary impact of nighttime sleep complaints on abdominal pain is indirect. The indirect effect appears primarily through daytime dysfunction. Such understanding provides a potential avenue to optimize personalized and hybrid behavioral interventions for adults with IBS through addressing daytime dysfunction and sleep behaviors. Additional study integrating symptoms with biological markers is warranted to explore the underlying mechanisms accounting for these symptoms. Manuscript three explored associations among chronotype, social jetlag (SJL) and weekday sleep outcomes (sleep quality, sleep need met and restorative sleep) in women with IBS through multiple linear regression analyses. This sample included 62 women with IBS (IBS predominant constipation [IBS-C] =29, IBS with predominant diarrhea [IBS-D] =33) and 58 healthy control (HC) women who completed 28-day daily diary from two study cohorts. Chronotype was estimated from daily diary data with the average mid-sleep time on weekends (MSWwe). SJL was calculated by subtracting the average mid-sleep time on weekdays from MSWwe. Sleep outcomes included diary-reported ratings of sleep quality, sleep need met and restorative sleep during weekdays. In HCs, later chronotype was predictive of lower sleep quality (β = -0.19, p < 0.01), a perception of sleep need not met (β = -0.17, p < 0.001) and a less restorative sleep during weekdays (β = -0.15, p = 0.073), whereas SJL was not associated with sleep outcomes. Similar to HCs, earlier chronotypes in women with IBS-C reported better sleep quality and more sufficient sleep need met and restorative sleep during weekdays than later chronotypes (all p > 0.05). Compared to HCs, the relationships of chronotype with weekday sleep outcomes in women with IBS-D were in the opposite directions (all p < 0.05). The data from this exploratory study suggest that chronotype may be an important contributor to sleep outcomes in women with and without IBS, particularly sleep quality and sleep need met.