Mental Imagery and Targeted Memory Reactivation in Insomnia

In this clinical trial, the investigators test whether mental Imagery Rescripting (IR), a technique where the individual is instructed to transform a negative memory or image into a positive one, and olfactory Targeted Memory Reactivation (TMR), a technique used to strengthen memories, can reduce hyperarousal and insomnia severity in patients with Insomnia Disorder (ID). Patients with ID will be randomized into four groups: in the first group (SH group), patients will have 4 weekly sessions (1 session/week) of a minimal intervention for insomnia (sleep hygiene information) in the presence of an odorless diffuser, which will be also used during the night. In the second group (IR group), patients will use IR during wakefulness to induce a state of relaxation and positive emotionality. More specifically, during 4 weekly sessions of IR, patients will imagine a negative scenario related to their pre-sleep images or current concerns (e.g., social interactions, self-image, sleep problem, nightmares) and transform it into a positive script. They will then perform IR every day for 4 weeks at home in the presence of an odorless diffuser, which will be also used during the night. In the third group, patients will undergo the same 4 weekly IR sessions and an odor will be paired to the positive imagery and will be diffused during the night (TMR group). Patients from this group will also perform IR every day for 4 weeks at home. Finally, the fourth group (OA group) will receive 4 weekly sessions of sleep hygiene instructions in the presence of an odor, which will be also used during the night. Clinical evaluation of insomnia severity before and after the intervention will take place using the Insomnia Severity Index (ISI, primary outcome measure). At the end of these interventions, patients with persistent symptoms will benefit from an alternative experimental treatment ("rocking bed") in which they will be cradled for one night. The investigators hypothesize that patients treated with IR will have significantly reduced insomnia severity compared to participants who received a minimal intervention. They also hypothesize that patients of the TMR group, will have more reduced ID severity compared to participants performing IR and with an odorless diffuser, therefore without an association (IR group). Finally, they hypothesize that one night of sleeping in a rocking bed will improve objective measures of sleep in ID compared to a stationary condition.