An interventional study of Overnight Active Temperature Regulation: Eight Sleep Pod System in Poor Sleep Quality, Gut Microbiome and Gut Health, sponsored by Eight Sleep Inc.. Recruiting at 1 site in United States. Open to participants aged 45 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-30.
Sponsored by Eight Sleep Inc. · Not applicable, Interventional, and Basic science
This study examines whether two continuous weeks of overnight active temperature regulation (via the Eight Sleep Pod) use affects gut microbiome composition, inflammation, and the body's daily temperature and blood pressure rhythms in postmenopausal women and age-matched men with self-reported poor sleep.
The goal of this study is to test whether improved sleep quality and stronger circadian patterns can improve gut health and decrease inflammation among postmenopausal women and men of a similar age. Previous research has documented the beneficial health outcomes from improved sleep quality. However, current research has yet to look at how overnight active temperature regulation can improve gut and cardiometabolic health. We will use the Eight Sleep Pod, a temperature-regulated mattress cover, to control bed temperature overnight. We want to see if this improves the community of bacteria in your gut, lowers inflammation in your body, and improves blood pressure and core temperature's natural 24-hour rhythms. We will test this idea with a group of men and women who are middle-age and older and say they sleep poorly. The women in the study will also be postmenopausal.
For men and women, the aging process often disrupts sleep quality. Specifically among women, the menopausal transition and the hormonal changes accompanying this life phase, changes sleep quality. Estrogen, a hormone that is relatively high for most of a woman's life, levels drop. This estrogen decline changes how a woman's body maintains a comfortable temperature, including at night. It also changes the body's natural 24-hour patterns, called circadian rhythms. As a result of these changes, women may experience broken sleep, hot flashes, and lower-quality sleep. Among men and women, broken and poor-quality sleep resulting from aging and the menopausal transition also affect your gut health, including the gut microbiome. This is the community of tiny organisms living in your digestive system. Broken and poor-quality sleep are also linked to more inflammation in your body. These effects feed into each other. Specifically, when sleep is disrupted, the balance of helpful versus harmful gut bacteria can shift, which can increase inflammation. Disrupted sleep harms your gut health, and poor gut health disrupts sleep even more. We think that improving sleep quality could improve gut health on its own, which will also improve inflammation throughout your body.
The Eight Sleep Pod is a mattress cover that controls bed temperature. It works throughout the night to actively regulate temperature as you sleep. Our previous research has shown that the Pod improves objective and subjective sleep quality, which is why we want to see if the Pod can improve other health metrics. This study will collect sleep, biological, and survey data during two weeks of sleep with the Pod's temperature control turned ON and two weeks with the control turned OFF. We will compare the data between the temperature conditions (ON \& OFF). We want to see if improving sleep quality leads to real changes in the gut microbiome, inflammation, core temperature, blood pressure, home sleep test and objective and subjective sleep quality metrics.
Findings from this study will advance scientific understanding of how improving sleep without medication could benefit gut and cardiometabolic (heart and metabolism) health in postmenopausal women and age-matched men. The findings will help guide future decisions to support health in these groups.
3,439 studies on the registry are indexed under Inflammation; 629 are open to participants now.
This study's planned enrollment of 100 is above the median of 50 across 2,437 interventional studies indexed under Inflammation.
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Inclusion Criteria: All Cohorts
Cohort A specific Inclusion: Postmenopausal women
Cohort B specific Inclusion: Age-Matched Men
-Assigned Male at birth
Exclusion Criteria: All Cohorts
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.
Anti-TNF-α medications (biologics for arthritis, Crohn's disease, psoriasis, or other immune/inflammatory conditions):
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):
Antihypertensive drugs (blood pressure 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
Hormone replacement therapy (exceptions: systemic - local vaginal estrogen preparations are not excluded):
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):
GLP-1 receptor agonists or other glucose-lowering 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
Stimulants affecting blood pressure:
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
Changed use status (started or stopped using) within 3 months before study start.
Current, ongoing, or history of diagnosis or changed diagnosis status (new diagnosis, revised or reversed diagnosis) within the specified timeframe.
Metabolic Conditions
Cardiovascular Conditions
Autoimmune Conditions
Gastrointestinal Conditions
Chronic Diseases
Neurological and Psychological Conditions
Sleep-Related Conditions
Participants will be excluded if they participate in any of the following behaviors or conditions within the indicated timeframe.
Substance Use
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
Health Status at Enrollment
---Acute illness or active infection at the time of recruitment or study start: includes colds, prolonged cough, fevers, etc.
Study Equipment Compatibility
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
Lifestyle and Compliance
Cohort A Exclusion Criteria: Postmenopausal women
Cohort B Exclusion Criteria: Age-Matched Men
-Diagnosed testosterone dysregulation (hyperandrogenism and/or androgen insufficiency)
All participants undergo Condition 1 (ATR ON, 2 weeks - 14 nights) followed by washout and Condition 2 (ATR OFF, 2 weeks - 14 nights).
Device: Overnight Active Temperature Regulation: Eight Sleep Pod System
Water-perfused mattress cover actively regulating temperature overnight, temperature will be ON during Condition 1 and OFF during Condition 2.
Gut Microbiome Composition
alpha diversity: Shannon Index, beta diversity: Bray-Curtis, F/B ratio, genus-level abundance, SCFA concentrations
Time frame: Preparation Period, End of Condition, End of Condition 2 (~5 weeks)
Systemic Inflammation (blood panel)
hsCRP levels
Time frame: Preparation Period, End of Condition, End of Condition 2 (~5 weeks)
Circadian Rhythm of Core Body Temperature
Circadian core body temperature (ingested core temperature capsule). Cosinor analysis will be performed with the data collected. The capsule will stay in the participant's system until naturally excreted (1-5 days). The data recorded will be output as a temperature value (in Celsius, °C) and at a sampling rate of one temperature reading per minute.
Time frame: Participants will ingest one capsule on Night 11 (second week of Pod ON condition) and Night 28 (second week of Pod OFF condition) 60 minutes before their normal bedtime. These are to evaluate the core body temperature between ON and OFF conditions.
Circadian Rhythm of Blood Pressure Rhythms
Blood Pressure (BP) Rhythms (systolic, diastolic, mean arterial pressure; MAP), including both single-point measurements and 24-hour ambulatory (mobile) measurements. The single-point BP readings will be manually enacted by the participant pressing the button on the monitor. During the 24-hour ambulatory monitoring, a BP reading will be taken every 30 minutes during the daytime and every 60 minutes once asleep, as per their reported normal bedtime. All BP readings are recorded and reported in millimeters of mercury (mmHg). The 24-hour BP readings will begin automatically 60 minutes before the participant's normal bedtime. Participants will continue wearing the BP cuff and monitor (attached to each other) for readings through the following night at that same time (therefore, it is a 24 hour reading). The protocol is marked in "Nights", however the metrics recorded in the day (AM) follow the same numerical convention (e.g. Day 11 = Night 11, where Night 11 is the nighttime of Day 11).
Time frame: 24-hour BP: Night -1 (Prep), Nights 5 & 12 (Pod ON), and Nights 22 & 29 (Pod OFF). Single-point BP (takes ~1-2 minutes): Night 11 PM & Night 12 AM (Pod ON), and Night 28 PM & Night 29 AM (Pod OFF). No BP readings occur during the 3-day washout period.
Objective Sleep Metrics: sleep staging, wakefulness after sleep onset and sleep onset latency (minutes)
Objective sleep metrics from sleep tracking devices (biometric tracking smart ring and Eight Sleep Pod) recorded in minutes. This includes sleep staging (N1: light sleep/N2: established light sleep/N3: deep sleep/REM: rapid eye movement) (minutes in each stage), wakefulness after sleep onset (WASO: tracks all periods of wakefulness following sleep onset, excluding the time it takes to fall asleep initially)(minutes), and sleep onset latency (the number of minutes it takes to transition from full wakefulness to the first stage of sleep).
Time frame: Objective sleep metrics are collected for the entire duration of the study (5-6 weeks total). The primary comparison for this outcome is objective sleep metrics (sleep staging, WASO, and sleep onset latency) between Pod ON and Pod OFF conditions.
Objective sleep metrics: Sleep efficiency (overall %)
Objective sleep metrics: Sleep efficiency (overall %) from sleep tracking devices (biometric tracking smart ring and Eight Sleep Pod). Sleep efficiency is the time spent asleep out of the total time spent in bed.
Time frame: Pod and biometric tracking smart ring data are collected for the entire duration of the study (5-6 weeks). The primary comparison for this outcome is objective sleep metrics (sleep efficiency, %) between Pod ON and Pod OFF conditions.
Objective sleep metrics: Nighttime Respiratory Rate (RR)
Nighttime Respiratory Rate (RR) from sleep tracking devices (biometric tracking smart ring and Eight Sleep Pod). RR is the number of breaths per minute while asleep (units: breaths per minute, BrPM).
Time frame: The Pod data and biometric tracking smart ring are collected for the entire duration of the study, for five weeks. The primary comparison for this outcome is objective sleep metrics (RR and BrPM) between Pod ON and Pod OFF conditions.
Subjective sleep quality metrics: Pittsburgh Sleep Quality Index (PSQI).
The PSQI measures sleep habits, patterns, and quality to assess perceived sleep quality. This assessment includes 19 self-rated items. The 19 items combine to form seven scored component categories, with each component assigned a score from 0 (no difficulty) to 3 (severe difficulty), with higher scores indicating greater sleep disturbance. All metrics obtained from the PSQI are subjective and reflect participants' perceptions of their sleep quality. The seven categories are: sleep quality, sleep latency (how long it takes to fall asleep), sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. The PSQI assessment computes a global score ranging from 0 to 21; a total score greater than 5 indicates poor sleep quality. The PSQI will be repeatedly administered across the duration of the study. A baseline PSQI score will be collected during recruitment as we will only be enrolling people with initially poor sleep.
Time frame: PSQI: Baseline during Preparatory Period (by Night 0); Pod ON at Nights 7 & 14; Pod OFF at Nights 24 & 31. No PSQI during the 3-day washout. Baseline may be completed anytime during the 5-day Prep; each PSQI reflects the preceding period.
Wellbeing will be assessed by the World Health Organization Well-Being Index (WHO-5).
The WHO-5 is a validated questionnaire that measures mental well-being over the two weeks prior to completion. The WHO-5 assessment consists of five questions, each of which are rated from 0 (at no time) to 5 (all of the time). The numbers reported from those five questions are added together to get a raw total score ranging from 0-25. The final score is derived by multiplying the raw score by 4 to get a percentage (%) score of 0 to 100. This assessment is interpreted as follows: a higher score suggests better well-being, a score of 50 or below suggests poorer well-being. Clinically, this assessment is used as a screening tool to gauge quality of life rather. It is not used to provide any formal diagnoses.
Time frame: Baseline score (%) during 5-day Preparatory Period (by Night 0); Pod ON at Night 14; Pod OFF at Night 31. Baseline may be completed anytime during Prep period. Pod ON/OFF scores reflect well-being over the prior 2 weeks. No WHO-5 during 3-day washout.
Quality of life, including physical, mental and social health, will be assessed with the Patient-Reported Outcomes Measurement Information System (PROMIS) survey, a standardized and validated assessment.
PROMIS measures pain, fatigue, depression, anxiety, sleep disturbances and physical functioning. Results of the assessment will use standardized T-scores where a score of 50 represents the average (mean) of the population, with a standard deviation of 10. Higher T-scores indicate greater levels of the concept being measured. For example, a higher score in negative domains, such as fatigue, indicates greater fatigue, while a higher score in positive domains, such as physical functioning, indicates better physical functioning. Scores are interpreted based on how far they are from the population average of 50. Whether a higher or lower score indicates a greater concern depends on what is being measured, and the domain being measured.
Time frame: Baseline score during 5-day Preparatory period (by Night 0); Pod ON at Night 14; Pod OFF at Night 31. Baseline may be completed anytime during Prep period. Pod ON/OFF scores reflect quality of life over the prior 2 weeks. No PROMIS during 3-day washout.
Menopausal symptom severity will be assessed for female participants with the Menopause Rating Scale (MRS),a validated questionnaire designed to assess the severity of menopausal symptoms.
The Menopause Rating Scale (MRS) consists of 11 items, each rated from 0 (no symptoms) to 4 (very severe symptoms). Item scores are summed to produce a total score ranging from 0 to 44. Higher scores indicate greater symptom severity. This assessment is interpreted as follows; 0-4 indicates no to mild symptoms, 5-8 indicates mild symptoms, 9-15 indicates moderate symptoms, and 16 or above indicates severe symptoms. A baseline MRS score will be collected during the Preparatory Period at the participants discretion, but required to be successfully submitted by the conclusion of the Preparatory Period (Night 0).
Time frame: Baseline score during 5-day Preparatory period (by Night 0); Pod ON at Night 14; Pod OFF at Night 31. Baseline may be completed anytime during Prep period. Pod ON/OFF scores reflect well-being over the prior 2 weeks. No MRS during 3-day washout.
Fatigue will be assessed with the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) scale,a validated questionnaire designed to assess fatigue and its impact on daily activities and function.
The FACIT scale consists of 13 items, each rated from 0 (not at all) to 4 (very much), reflecting the previous seven days. Item scores are summed, with reverse scoring applied to negatively worded items, to produce a total score ranging from 0 to 52. For example, a response of 4 on a negatively worded item would be scored as 0, while a response of 0 would be scored as 4. Higher scores indicate less fatigue. A baseline FACIT score will be collected during the Preparatory Period at the participants discretion, but required to be successfully submitted by the conclusion of the Preparatory Period (Night 0).
Time frame: Baseline score during 5-day Preparatory period (by Night 0); Pod ON at Night 14; Pod OFF at Night 31. Baseline may be completed anytime during Preparatory period. Pod ON/OFF scores reflect fatigue over the prior 2 weeks. No FACIT during 3-day washout.
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