Individuals with chronic insomnia have persistent difficulty falling and staying asleep, as well as complaints of altered daytime functioning that may be associated with cognitive impairments. The neural processes underlying these daytime complaints may involve abnormal activation of brain regions and neural networks involved in working memory, memory encoding and emotions. The goal of this study is to assess whether a psychological treatment for insomnia will reverse these abnormalities in brain responses to cognitive tasks and at rest. A secondary objective of the study is to characterize impairments in attentional processing and assess if the impairments can be reversed by the psychological treatment. We hypothesized that the psychological treatment for insomnia will lead to a normalization of the brain responses to working memory, declarative memory encoding, insomnia-related stimuli, and the functional connectivity within the default-mode and limbic networks.

Study hypothesis

Brain responses associated with working memory task and declarative memory encoding will be decreased in chronic insomnia compared to good sleepers and, among individuals with chronic insomnia, cognitive-behavioral therapy for insomnia will lead to larger recovery in these brain responses, compared to a 3-month wait period.

Brain responses to emotional stimulation, especially to insomnia-related stimuli, will be increased in chronic insomnia compared to good sleepers, and, among individuals with chronic insomnia, cognitive-behavioral therapy for insomnia will lead to larger reduction in these brain responses, compared to a 3-month wait period.

Connectivity in the default-mode and limbic networks during resting-state will be increased in chronic insomnia compared to good sleepers, and, among individuals with chronic insomnia, cognitive-behavioral therapy for insomnia will lead to larger reduction in this connectivity, compared to a 3-month wait period.

Inclusion Criteria:

80 participants with chronic primary insomnia (40 per group) 40 good sleepers

Exclusion Criteria:

1. Older than 65 y.o. or younger than 25 y.o.
2. Contraindication to the MRI scanning
3. Current neurological disorder
4. Past history of brain lesion
5. Major surgery (i.e., requiring general anesthesia) in the past 3 months
6. Untreated thyroid disorder
7. Chronic pain syndrome self-reported as interfering with sleep
8. Recent and severe infection in the past 3 months
9. Active cancer, or remitted cancer with cancer treatment within the last 2 years
10. Stroke
11. Myocardial infarct
12. Arterial bypass or angioplasty
13. Pacemaker
14. Heart failure causing limitation of ordinary physical activity
15. Renal insufficiency
16. Sleep apnea with an apnea-hypopnea index > 5/h
17. Restless legs syndrome with symptoms 3 days or more per week
18. Periodic limb movements during sleep with index > 15/h
19. REM-sleep behavior disorder
20. Narcolepsy and other central disorders of hypersomnolence
21. Sleepwalking more than once/month
22. Having worked on night shifts or rotating shifts for more than 2 weeks in the last 3 months or expecting to do so during the study period
23. Severe mental disorders: bipolar disorder (Type I), schizophrenia, anxiety disorders, major depressive disorder, current substance use disorder, current post-traumatic stress disorder
24. Current suicidality
25. Frequent alcohol consumption (>10 glasses/week) or use of cannabis (more than once a week) or illicit drugs (more than once a month)
26. Smoking cigarettes more than 10 cigarettes/day
27. Pregnant or breastfeeding women
28. Current psychotherapy or past cognitive-behavioural therapy for insomnia
29. Current use of medication for depression or anxiety
30. Unable to stop hypnosedative medications for at least 2 weeks prior to the first assessment
31. For good sleepers: insomnia symptoms more than 3 times/ week.