Deep Sleep in Older Adults

Inclusion Criteria 1. Fluent English speaker and reader. 2. Capable of providing one's own informed consent. 1. As determined by validated, abbreviated phone-based remote Montreal Cognitive Assessment (MoCA) testing score of ≥18, which is the score that separates Mild Cognitive Impairment (MCI) from Alzheimer's Disease and Related Dementia (ADRD). 3. Age 55+ years old (inclusive) at enrollment. a. As self-reported on screening survey and later verified in video appointment (e.g. Zoom Health) 4. If residing in a community residence (such as a retirement community) in which a Medical Director designates living status categories, then the participant must be Independent Living status (or equivalent). 1. As self-reported on screening survey 5. Insomnia Severity Index score ≥15 (i.e., at least "clinical insomnia," that is "moderate-to-severe") - but if recruitment is slow then the investigators will recruit with ISI score ≥11 "mild-to-severe"). a. As self-reported on the ISI screening survey 6. Willing to refrain from initiating new therapeutic interventions (e.g. medication; behavioral) that are not a part of this study protocol for issues pertaining to sleep for the duration of study participation. a. By self-report 7. Willing to maintain any existing physician-directed pharmacologic intervention for issues pertaining to sleep for the duration of study participation. a. By self-report 8. Has a residence with WIFI. a. By self-report 9. Normal hearing with or without a hearing aid. a. By self-report 10. Difficulty falling asleep, staying asleep, or waking too early, occurring at least 3 nights/week for 3+months, causing significant daytime distress/impairment (e.g., fatigue, poor focus, mood issues), despite adequate sleep opportunity, and not better explained by another sleep disorder or substance. 1. By Sleep Condition Indicator \[SCI\] Exclusion Criteria 1. Illicit drug use in the past month (except for marijuana because it is legal in many States, and the investigators are recruiting nationwide). a. As self-reported on screening survey. Marijuana usage will be tracked via self-report and examined as a moderator. 2. Diagnosed serious mental health disorder. 1. Specifically, psychosis or bipolar depression, severe major depression, moderate to high risk of suicide, dementia 2. As self-reported on screening survey 3. Currently or recent engaged (past 1-year) in evidence-based psychotherapy for Insomnia (e.g., CBTi), in addition to ever receiving a full course of CBTi: a. By self-report 4. Cohabitating with a current or previous participant in this study. a. This criterion is to avoid cross-contamination of study condition awareness, if two cohabitating individuals are randomized into different study arms. 5. Initiation of any psychological treatment in the last 3-months. 6. A highly irregular schedule (e.g. shift work) that would prevent adoption of intervention strategies, as evaluated through the Shift Work Disorder Index. 7. Previous exposure to the SleepSpace software. 8. Medical conditions that are exacerbated by sleep restriction. 9. Planned major surgery during the trial.