Sleep quality and the self: an investigation of the relationship between sleep quality and the multidimensional self

Abstract

The self and sleep are two of the most widely investigated psychological phenomena, but limited research has examined their isolated relationship. Such research has focused primarily on how subjective sleep quality relates to individual dimensions of the self, such as self-esteem or self-control. In this PhD thesis, I present four studies that aim to clarify the relationship between sleep quality and the self, on a more holistic level. I am particularly concerned with four self-constructs – self-compassion, self-control, self-esteem, self-continuity – although I test exploratorily an assortment of others. This research utilises cross-sectional and longitudinal, as well as subjective and objective, methods. Study 1 revealed that sleep quality was positively related to self-compassion, self-control, self-esteem, and self-continuity at the trait level; but held no significant relationship with self-expression, self-enhancement, or self-concept clarity . At the state level, three succeeding longitudinal diary studies (Studies 2-4) reinforced these significant findings, focusing only on self-control, self-compassion, self-esteem, and self-continuity. Study 2 revealed a predictive effect of subjective sleep quality on all four self-constructs, but no predictive effective of these self-constructs on subjective sleep quality. Study 3 used actigraphy to objectively measure sleep efficiency. Here, subjective sleep quality predicted self-control, self-continuity, and self-esteem (trendingly), but not self-compassion. Objective sleep quality did not predict any self-construct. In the reverse direction, none of the self-constructs predicted subjective sleep quality, although objective sleep quality was predicted by self-compassion and self-continuity. Study 4 implemented experimental manipulations to increase effortful self-compassion, self-control, and self-esteem. This method aimed to amplify the effect of these self-constructs on subjective sleep quality, relative to the typical (effortless) behaviours of Studies 2 and 3. Results show that subjective sleep quality predicted all three self-constructs, and also subjective sleep quality was predicted by self-compassion and self-esteem, but not self-control. S Taken together, this PhD thesis is the first to identify a bidirectional predictive relationship between sleep quality and multiple dimensions of the self.
Keywords: Sleep Quality; Self-Compassion, Self-Control, Self-Esteem, Self-Continuity.

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Identifiers

ORCID for James Butterworth: orcid.org/0000-0002-0867-7353

ORCID for Nicholas Kelley: orcid.org/0000-0003-2256-0597

ORCID for Tim Wildschut: orcid.org/0000-0002-6499-5487

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