Disturbed Sleep and its Association with Poor Mental Health

Abstract

Sleep is an essential physiological process with a variety of functions. Disturbed sleep is common across mental health disorders and demonstrates a close relationship, with poor sleep predisposing to mental health problems, as well as being a symptom of them. I have conducted four studies into aspects of poor sleep and mental health using differing methodologies. Firstly, a meta-analysis into sleep and emotional reactivity in experimental studies (n=24 studies), which found that self-reported arousal ratings of negative stimuli were significantly increased post-sleep but not post-waking. However, such studies need more consistency in methodology. Secondly, a cross-sectional analysis of sleep measures on the Hamilton Anxiety and Hamilton Depression scales in a sample of young adult gamblers. This found that gambling disorder is associated with higher levels of anxiety and depression, reaching a clinical cut-off, as well as insomnia symptoms. Thirdly, I performed a longitudinal analysis of sleep symptoms as measured by the Pittsburgh Sleep Quality Index (PSQI) in the women who participated in the NiPPeR Randomised Controlled Trial. Group-based trajectory modelling identified that those reporting fewer hours of sleep at preconception typically also had shorter sleep during pregnancy and post-delivery. More than 30% of women had a clinically significant PSQI score >5 maintained throughout, indicating persistent substantial sleep difficulties. The group of worst sleepers had significantly higher levels of anxiety and depression throughout pregnancy. Finally, I examined the relationship between Vitamin D deficiency, sleep, depression and anxiety in the NiPPeR RCT. Sleep quality was worse in Vitamin D deficient participants only at preconception. There was a significantly higher level of depression in those who were Vitamin D deficient at preconception and at 7 weeks gestation, but not at 28 weeks gestation or at 6 months post-delivery. There was no impact of Vitamin D status on anxiety symptoms. Collectively this thesis underscores the close relationship between poor sleep and poor mental health. This research contributes to a more nuanced understanding of how sleep impacts mental health in different contexts. It focusses on specific under-researched groups including young adult gamblers and women in the perinatal period, who may present a future target for the primary prevention of mental health difficulties by addressing sleep problems at an earlier stag