Optimizing an Integrated Mind and Body Treatment for Insomnia: The SLEEPS Study 2

Inclusion Criteria:

* 18 years or older
* English-speaking
* Willing to use birth control if assigned female sex at birth
* Willing to receive study text messages during participation
* Location to plug sauna blanket into regular wall outlet
* Ability to lie in sauna blanket for 15 minutes
* Ability to fit in the sauna blanket
* Daily access to the internet via computer, smartphone, or tablet
* Elevated insomnia symptoms as indexed by a score of 11 or greater on the Insomnia Severity Index (ISI) at two screening timepoints
* Primary insomnia disorder (characterized by difficulty initiating sleep) as indexed by a positive diagnosis on the Structured Clinical Interview for DSM-5 Sleep Disorders (SCISD)

Exclusion Criteria:

* Night shift or swing shift worker
* Current or planned routine body heating practices (e.g., saunas, hot tubs, long baths) within 4 hours before bed that are 10 minutes or more in duration (≥2x per week)
* Pregnant or plans to become pregnant during the participation period
* Traveling internationally between screening assessment and anticipated post-intervention assessment, or during anticipated post-follow-up assessment period (\~1 week)
* Other diagnosed sleep disorders or suspected sleep disorders
* Medical conditions that might increase the risk of passive body heating using an infrared sauna blanket
* Medication use that might increase the risk of passive body heating using an infrared sauna blanket
* Mental health disorder that may better explain insomnia, require priority treatment, or be exacerbated by time in bed restriction
* Medical condition that may better explain insomnia, require priority treatment, or be exacerbated by time in bed restriction
* Lifetime diagnosis of a bipolar disorder, psychosis, or other psychotic disorder
* Current (past 3 months) major depressive disorder
* Current (past 12 months) suicidality, alcohol use disorder, other substance use disorder (except mild cannabis use disorder), panic disorder, agoraphobia, social anxiety disorder, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, post-traumatic stress disorder, and eating disorders
* If using medications for mental health treatment (e.g., antidepressant medication) must have been on a stable dose for prior 8 weeks
* Currently receiving cognitive behavioral therapy for insomnia (CBT-I)