Overnight Temperature Regulation to Test Gut Health, Inflammation, and Circadian Rhythms

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 colds, prolonged cough, fevers, etc.
  * Active cancer diagnosis or receipt of chemotherapy or radiotherapy within 12 months prior to study start, or planned chemotherapy treatment during the study duration
  * Hospitalization of greater than 24 hours for acute illness, major surgery, sepsis, or cardiac, pulmonary or neurological events within 6 months prior to study start

Case-by-Case Eligibility Review

* Purpose: Participants are not automatically excluded for the medications, supplements, conditions, or specific changes listed below. These items are collected so the study team can judge whether each one is likely to (a) affect participant safety, (b) interfere with the study's primary outcomes (gut microbiome, inflammation, circadian temperature and blood pressure, sleep), or (c) make the participant unable to complete study procedures.
* Process

  1. Collection. Medication, supplement, condition, and routine-change information is collected in the Recruitment Survey and Health History Survey. Responses that match a listed item are flagged for review. They are not used to automatically screen out the participant.
  2. Reviewer. Flagged responses are reviewed by the study staff.
  3. Follow-up. The research team may contact the participant to clarify details (for example medication name, dose, how long it has been taken, whether the condition is stable or active, or the date of a recent change). The team will make it clear that they do not need to disclose this information if they do not wish or are uncomfortable doing so.

     * Factors considered.

       * Safety risk to the participant from study procedures or devices
       * Whether the condition or medication is stable, well-controlled, and long-standing
       * How long ago a change happened, and whether further change is planned
       * Likely effect on gut microbiome, inflammation, blood pressure, core temperature, or sleep measures
       * Ability to complete study procedures
       * Number and combination of flagged items for the same person

     Possible decisions. A.Eligible. The item does not meaningfully affect safety or outcomes. B.Eligible with conditions or a delayed start. For example, waiting until a recent change has been stable for a set period.

     C.Not eligible. Safety or data-integrity concerns are too great.
  4. Communication. Participants are told the outcome. Participants found not eligible are told in neutral language, and no study data are collected from them beyond screening information.
  5. Data handling. Screening information from individuals who are not enrolled is stored securely and not used for future research (consistent with the Health History Survey privacy statement).

Section 1 \| Medications \& Supplements

* Use status is specified per section. Medications and supplements include common examples of the respective substance. Please note that this criteria is not limited to the provided examples and it is the responsibility of the potential participant to identify and accurately report their medication or supplement type and use status.

  --1.1 Anti-Infective and Anti-Inflammatory Medications
  * Currently taking any of the following medications/supplements or have changed use status (using to not using or vice versa) within 3 months before study start.
  * Antibiotics (any kind), including one-time or short-term antibiotic use
  * Corticosteroids (oral or injection only, topical preparations included):
  * Prednisone
  * Prednisolone
  * Dexamethasone
  * Hydrocortisone
  * Methylprednisolone (Medrol)
  * Budesonide
  * Betamethasone
  * Anti-TNF-α medications (biologics for arthritis, Crohn's disease, psoriasis, or other immune/inflammatory conditions):
  * Adalimumab (Humira)
  * Etanercept (Enbrel)
  * Infliximab (Remicade)
  * Certolizumab (Cimzia)
  * Golimumab (Simponi)
* 1.2 Cardiovascular Medications --Changed use status (using to not using or vice versa) within 3 months before study start or plans to stop/start the medications during the study.

  * Statins (cholesterol-lowering medications):
  * Atorvastatin (Lipitor)
  * Rosuvastatin (Crestor)
  * Lovastatin (Mevacor)
  * Fluvastatin (Lescol)
  * Antihypertensive drugs (blood pressure medications):

Angiotensoconverting enzyme (ACE) inhibitors: Lisinopril, Ramipril, Perindopril, Enalapril

* Angiotensin II receptor blockers (ARBs): Losartan, Valsartan, Candesartan
* Calcium channel blockers: Amlodipine (Norvasc), Diltiazem, Verapamil
* Beta-blockers: Metoprolol, Atenolol, Bisoprolol, Propranolol
* Diuretics: Hydrochlorothiazide, Furosemide (Lasix), Indapamide

  -1.3 Hormonal Medications

  --Changed use status (using to not using or vice versa) within 3 months before study start or plans to start/stop during the study.
* Hormonal birth control (any form):

  * Combined oral contraceptives (estrogen + progestin) or progestin-only capsule
  * Hormonal IUD (e.g. Mirena, Kyleena)
  * Contraceptive implant (e.g. Nexplanon)
  * Contraceptive injection (e.g. Depo-Provera)
  * Contraceptive patch (e.g. Xulane, Evra)
  * Vaginal ring (e.g. NuvaRing)
* Hormone replacement therapy (exceptions: systemic - local vaginal estrogen preparations are not excluded):

  * Estrogen-based: oral tablets, patches, gel, cream, or vaginal ring
  * Combined estrogen + progestogen: oral tablets or patches
  * Progesterone-based: oral tablets or intrauterine device
  * Testosterone: cream or gel
  * Bioidentical: oral tablets, patches, gel, cream, pellets, or injections

    * Currently taking any of the following medications/supplements or have changed use status (using to not using or vice versa) within 3 months before study start or plans to start/stop during the study.
* Anabolic-androgenic steroids or performance-enhancing drugs (prescribed or non-prescribed):
* Testosterone-based: testosterone enanthate, cypionate, propionate, Sustanon
* Synthetic anabolic steroids: nandrolone, stanozolol (Winstrol), oxandrolone (Anavar), methandrostenolone (Dianabol), trenbolone
* GLP-1 receptor agonists or other glucose-lowering medications:
* GLP-1s: Semaglutide (Ozempic, Wegovy), Liraglutide (Victoza, Saxenda), Dulaglutide (Trulicity), Tirzepatide (Mounjaro, Zepbound)
* Other: Metformin (Glucophage), Insulin (all types), Sitagliptin (Januvia), Empagliflozin (Jardiance), Dapagliflozin (Farxiga), Glipizide, Glyburide

  -1.4 Sleep and Psychoactive Medications

  --Currently taking any of the following medications/supplements or have changed use status (using to not using or vice versa) within 3 months before study start or plans to start/stop taking these drugs during the study period.
* Sleep medications:

Prescription: Zolpidem (Ambien), Zopiclone (Imovane), Eszopiclone (Lunesta), Temazepam, Nitrazepam, Trazodone (when prescribed for sleep), Suvorexant (Belsomra)

* Over-the-counter: Diphenhydramine (Benadryl, ZzzQuil, Unisom), Doxylamine (Unisom SleepTabs, Nytol),
* Benzodiazepines (use status change within 12 months before study start):

Diazepam (Valium), Lorazepam (Ativan), Clonazepam (Klonopin), Temazepam, Nitrazepam

* Antidepressant medications (change within 3 months of study start or plans to start/stop taking during the study period)
* Stimulants affecting blood pressure:
* Methylphenidate (Ritalin, Concerta)
* Amphetamine/Dextroamphetamine (Adderall)
* Lisdexamfetamine (Vyvanse)
* Modafinil (Provigil)
* Pseudoephedrine (Sudafed, including other cold/decongestant medications)
* Antipsychotics: Quetiapine (Seroquel), Olanzapine (Zyprexa), Risperidone
* Mood stabilizers: Lithium, Valproate (Depakote)

  --Changed use status (using to not using or vice versa) within 3 months before study start or during the study.
* CBT-I or pharmacological treatment for insomnia disorder

  -1.5 Supplements

  --Changed use status (started or stopped using) within 3 months before study start.
* Probiotics, prebiotics, or synbiotics
* SCFAs
* Butyrate (Sodium butyrate, Calcium/magnesium butyrate, Tributyrin), Acetate, ---Propionate
* Multivitamins containing any of the following minerals:

Iron, Selenium, Calcium, Zinc, Phosphorus, Magnesium

* Note: Stable long-term multivitamin use (unchanged for ≥3 months) is not excluded

  * Folic Acid, Vitamin C, Vitamin A, Vitamin D, or Vitamin E supplements
  * Antioxidant supplements
  * Omega-3 / fish oil supplements
  * Melatonin (current use excluded if unwilling to cease use during study participation)

    * Section 2 \| Conditions

      --Current, ongoing, or history of diagnosis or changed diagnosis status (new diagnosis, revised or reversed diagnosis) within the specified timeframe.
    * 2.1 Metabolic Conditions

      * Diabetes mellitus: Type 1
      * Type 2 diabetes (within the past 3 years)
      * Diagnosed prediabetes (confirmed via Preparation Period hbA1c levels. A result between 5.7-6.4% warrants exclusion from the study)
      * Chronic hepatitis B/C
      * Liver cirrhosis
      * Alcoholic liver disease
      * Non-alcoholic fatty liver disease (NAFLD) or non-alcoholic steatohepatitis (NASH) (within the past 3 years)
      * Hepatitis A (within the past 3 years)
      * Hypothyroidism or hyperthyroidism (including Hashimoto's thyroiditis)
    * 2.2 Cardiovascular Conditions

      * Hypertension
      * Cardiovascular disease, including:
      * Coronary artery disease (CAD) or ischemic heart disease
      * History of myocardial infarction (heart attack)
      * Heart failure (any grade)
      * Atherosclerosis
      * History of stroke or transient ischemic attack (TIA)
      * Peripheral arterial disease (PAD)
      * Atrial fibrillation or other major cardiac arrhythmias
      * Vasovagal syncope: common fainting episode caused by a sudden drop in blood pressure and heart rate
      * Severe anemia or significant white blood cell or platelet abnormalities
      * Surgery, severe skin disease, or fistula on the upper arm (interfering with BP cuff readings; within 3 months prior to the study start)
    * 2.3 Autoimmune Conditions

      * Rheumatoid arthritis
      * Ankylosing spondylitis
      * Lupus erythematosus
      * Multiple sclerosis (MS)
      * Any other diagnosed autoimmune condition or current use of immunosuppressive medications
    * 2.4 Gastrointestinal Conditions

      --Inflammatory bowel disease (IBD), Crohn's disease or ulcerative colitis
      * Irritable bowel syndrome (IBS)
      * Celiac disease
      * Gastroparesis or diverticular disease
      * History of colostomy, colon cancer, or other colon-related surgeries
      * Recent gastrointestinal surgery (within 6 months prior to enrollment)
    * 2.5 Chronic Diseases

      --Renal disease (chronic kidney disease, any stage)
      * Hepatic disease (beyond those listed under metabolic conditions above)
      * Respiratory or chronic lung disease
    * 2.6 Neurological and Psychological Conditions

      --Dementia
      * Alzheimer's disease
      * Parkinson's disease
      * Schizophrenia
    * 2.7 Sleep-Related Conditions

      --Obstructive sleep apnea (OSA)

      --Central sleep apnea

      --Complex sleep apnea syndrome

      --Narcolepsy or hypersomnia disorders
      * Restless legs syndrome (RLS) / Willis-Ekbom disease
      * Periodic limb movement disorder (PLMD)
      * Circadian rhythm sleep-wake disorders: shift work disorder (SWD), irregular sleep-wake rhythm disorder (ISWRD), or non-24-hour sleep-wake disorder (N24SWD) \*Note: Participants with delayed sleep-wake phase disorder (DSWPD) or advanced sleep-wake phase disorder (ASWPD) with chronically stable sleep timing may be included.
    * Section 3 \| Current Behaviors and Conditions --Participants' responses will be reviewed to determine eligibility if they participate in any of the following behaviors or conditions within the indicated timeframe.
    * 3.1 Substance Use

      --Current addiction to opiates

      --Excessive alcohol consumption (more than 14 standard drinks per average 1 week)

      --Habitual caffeine consumption exceeding 400 mg per day (approximately 4 standard cups of coffee or equivalent)

      --Recreational frequent drug use within timeframes noted prior to study start:

      --Cannabis / marijuana (including edibles and oils): daily or near-daily use (defined as ≥5 days per week) within 3 months prior to study start

      --Cocaine: any use within 3 months prior to study start

      --MDMA / ecstasy: any use within 3 months prior to study start

      --Hallucinogens (LSD, psilocybin): any use within 4 weeks prior to study start

      --Ketamine or other illicit substances: any use within 3 months prior to study start
    * 3.2 Diet and Weight --Planning significant changes to diet or lifestyle in the 3 months prior to study start, or had significant changes to diet or lifestyle in the 3 months prior to study start --Starting or stopping a specialized diet (ketogenic, vegan, carnivore, elimination, intermittent fasting) --Significant increase or decrease in exercise load or training plan (change of ≥60 minutes per week in total exercise volume, starting or stopping a structured exercise program, or injury/illness-related activity restriction) within 3 months prior to study start --Currently enrolled in an active weight-loss program, bariatric program, or medically supervised diet, or planning to start one during the study --Weight loss or gain within the past 1 month of 5% of body weight or greater, or weight loss or gain within the past 6 months of 10% body weight or greater

Additional Cohort-Specific Exclusion

* Cohort A: Postmenopausal Women

  * Reproductive \& Endocrine Conditions

    ---Hysterectomy

    ---Oophorectomy (single or double)

    ---Polyendocrine metabolic ovarian syndrome (PMOS), previously known as polycystic ovarian syndrome (PCOS)

    ---Diagnosed testosterone dysregulation (hyperandrogenism or androgen insufficiency) not attributable to PMOS

    ---Premature ovarian insufficiency (POI) or premature ovarian failure (POF)

    ---Endometriosis

    ---Change to hormone replacement therapy (HRT) use within 3 months prior to study start

    ---Changes to hormonal birth control use within 3 months prior to study start
* Cohort B: Age-matched men --Diagnosed testosterone dysregulation (hyperandrogenism and/or androgen insufficiency)