Rest to Overcome Loss and Reduce Risk (RESTore Plus)

Inclusion Criteria: 18 years or older Has experienced the loss of a spouse/long-term cohabitating partner (i.e., partner who lived with participant for at least 1 year before passing) within the past 3 months Scores 5 or above on the Pittsburgh Sleep Quality Inventory (PSQI; administered by research staff during phone screening call) Must have access to an internet-enabled device (e.g., smartphone, computer, tablet) to take part in the online intervention Exclusion Criteria: Under age 18 Non-English speakers Those with a previously diagnosed sleep disorder (e.g., restless leg syndrome; note: individuals with obstructive sleep apnea (OSA) will be eligible as long as they use a continuous positive airway pressure (CPAP) machine at least 5 days a week for at least 5 hours per day) Those who have been taking prescribed sleep medication(s) for 6 months or more Those with autoimmune or inflammatory diseases (such as: acute or chronic immune system medical conditions, medications or other conditions that impact immune function (e.g., chronic fatigue syndrome [CFS], lupus, rheumatoid arthritis, Sjogren's disease, systemic lupus erythematosus [SLE], Hepatitis C, or any other immunosuppressive treatment requiring conditions, per investigator discretion). Those who regularly use illegal substances. Those who are on medications with major immunological consequences (e.g. steroids) Women who are pregnant or nursing Those who have been vaccinated in the past two weeks (note: these individuals may simply delay enrollment by two weeks if otherwise eligible) Those with significant visual or auditory impairment, medical or psychiatric condition that is unstable, requires immediate treatment or is judged to interfere with study protocol (e.g., substance abuse, psychotic disorder, cognitive disorder, current suicidal ideation)