The Impact of Overnight Active Temperature Regulation on the Gut Microbiome, Inflammation, and Circadian Rhythm.

Eligibility is determined in three parts: * Inclusion criteria. All must be met. * Exclusion criteria. If any applies, the individual is not eligible. These include criteria that affect participant safety, device compatibility, study logistics, or the ability to consent. They are not reviewed case-by-case. * Case-by-case eligibility review. Medications, supplements, medical conditions, and recent changes in health or routine are collected through the Recruitment Survey and Health History Survey. They do not automatically exclude a participant. Each reported item is reviewed individually by the study team (see "Case-by-Case Eligibility Review" below). Inclusion Criteria - All Cohorts * All of the following criteria, assessed via the Recruitment Survey and Health History Survey, must be met for an individual to be eligible to participate. Initially eligible individuals will complete a post-enrollment blood panel to confirm hsCRP values. The hsCRP value from the blood panel will influence the final inclusion decision on a case-by-case basis. * General \& Demographic * 45 years of age or older * Self-reported poor sleep quality: PSQI score greater than 5 * Within 1.5 hours driving of the Greater Boston area * Have never used an Eight Sleep Pod (or similar device) ever * Health, Physiological, \& Logistics * Post-enrollment hsCRP ≤ 10 µg/mL at Preparation Period blood panel. If Preparation Period hsCRP \> 10 µg/mL: triggers clinical review on a case by case basis; hard exclusion applies only at \> 30 µg/mL * Weight ≥ 88 lbs * No MRI scheduled during the study period or within 1 week after study conclusion * No acute illness, injury, or dental procedure/cleaning within 3 months prior to study start * Non-smoker or previous infrequent (\<1 weekly) smoker who has ceased at least 3 months prior to study start * Predictable bowel movements: at least 3 weekly and no more than 3 daily bowel movements * Able to drive or be transported to a local lab facility at least three total times for blood panels * Willing to complete 3 blood panels (3-4 tubes of blood collected at each draw): no strong aversion to needles * Able to swallow a pill/capsule (approximately the size of the standard vitamin capsule) for internal core temperature monitoring * Diet \& Medication Stability * Stable diet for a minimum of 3 months prior to enrollment, with no planned major dietary changes during the study period * Stable medication regimen: no medication type or dose changes within 3 months prior to study start, and no plans to change medications during the study. This includes long-term medication like antidepressants, statins, hormones, antihypertensives, or levothyroxine. * Stable exercise routine for a minimum of 3 months prior to study start, with no planned changes to this routine * Stable dietary supplement routine for a minimum of 3 months prior to the study start: includes probiotics, synbiotics, supplemental SCFA's * Lifestyle \& Compliance * Willing to receive, set-up, and use all required equipment: the Eight Sleep Pod Cover and Hub, biometric smart ring, urine-based hormone measurement kit, ambulatory blood pressure monitor, core temperature capsule, HST device, and stool collection kits for the required amount of time * Comfortable using research accounts owned by Eight Sleep for some study devices * Willing and able to have stool samples picked up by the research team three and up to five times during the study * Willing to have the research team in the home for study set-up (up to 3 hours) ---Have a valid, government issued ID * Cohort A Inclusion Criteria: Postmenopausal Women * Assigned female at birth * Postmenopausal: self-reported absence of menstrual period for 12 or more consecutive months prior to study start * No change to hormone replacement therapy (HRT) use within 3 months prior to study start or plans to change HRT status during study period * No changes to hormonal birth control use within 3 months prior to study start or plans to change birth control use during study period * Cohort B Inclusion Criteria: Age-Matched Men * Assigned male at birth * Age-matched to female participant group Exclusion Criteria - All Cohorts: No case-by-case review Participants will be excluded if they meet any of the following criteria outlined below. * 1.1 Study Equipment Compatibility * Unable or unwilling to swallow a standard-sized capsule (required for internal core temperature monitoring capsule) * Currently using a pacemaker or other electromagnetic medical implant (contraindicated with core temperature capsule) * MRI scheduled during the study period or within 1 week after study conclusion * Have or may have a CT scan planned during the study period * Allergic to nickel or aluminum * 1.2 Sample and Data Collection * Unable or unwilling to * Collect and provide at least 3, and up to 5, stool samples * Store self-collected stool samples in a home freezer until shipment/pick-up (up to 1 week after collection) * Complete 3 blood panels (3-4 tubes of blood each), including strong aversion to needles * Complete required digital surveys and any requested data sharing * Communicate with the research team within a timely manner throughout the duration of the study * Have stool samples picked up from home * Have research staff within home for study set-up for up to 3 hours * Complete all data collection requirements in a timely manner * 1.3 Lifestyle and Compliance * Travel planned during the study period * Unstable WiFi connection at any point during the study period (to the best ability this can be predicted) * Unwilling or unable to provide informed consent with sufficient mental wellness to understand the study * Lived outside of the United States within 6 months prior to study start * 1.4 Health Status at Enrollment * Acute illness or active infection at the time of recruitment or study start: includes col