ORCID

Abstract

Functional Imagery Training (FIT) is a brief motivational intervention grounded in the Elaborated Intrusion theory of desire. It helps individuals use personalised, emotionally vivid mental imagery to support goal pursuit by drawing on past successes to plan actions, overcome obstacles, and rehearse behavioural strategies. Delivered in the client-centred style of Motivational Interviewing (MI), FIT aims to strengthen motivation for sustained behaviour change. While FIT has shown promise in areas such as weight loss and anxiety, its application to sleep-related behaviour change remains unexplored. This single-arm pilot study examined whether FIT is associated with improvements in sleep quality and motivation to engage in sleep hygiene behaviours. It also explored whether the hypothesised mechanism, the development and practice of motivational imagery use, mediates changes in sleep outcomes. Thirty-one participants with self-reported sleep difficulties completed a one-hour remotely delivered FIT session and two follow-up calls. Measures of sleep quality and motivation were collected at baseline, two weeks post-intervention, and one-month follow-up. Imagery use was assessed at post-intervention and follow-up only. Bayesian analysis provided strong evidence for increased motivation maintained over time but inconclusive evidence for improvements in sleep quality. There was no evidence that imagery quality or practice directly contributed to motivational gains. However, qualitative feedback suggested FIT was perceived as supportive and helpful for behaviour change. Findings suggest FIT may be effective for enhancing motivation in individuals with sleep problems. Longer follow-up periods and further controlled trials are needed to evaluate FIT’s impact on sleep quality and clarify its mechanisms of change.

Awarding Institution(s)

University of Plymouth

Supervisor

Jackie Andrade

Keywords

Functional Imagery Training, behaviour change, motivation, sleep quality

Document Type

Thesis

Publication Date

2025

Embargo Period

2026-09-08

Deposit Date

September 2025

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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