Contributed by Megan Holm, M.S.
Sleep science has traditionally relied on short laboratory studies, small sample sizes, and populations that don’t reflect how people actually sleep at home. This is especially true for women in midlife, a group that has been historically underrepresented in sleep research, despite reporting some of the most significant sleep challenges.
In the summer of 2025, Eight Sleep Labs set out to change that. We launched one of our largest research efforts to date: a real-world, longitudinal study designed to investigate how nighttime temperature regulation affects sleep, physiology, and recovery, focusing on menopausal women. This single study collected the first, and largest, dataset of continuous core body and skin temperatures collected from people sleeping on the Pod and produced two scientific manuscripts now under submission for peer-review (and currently live on preprint servers: nocturnal hot flashes, body temperature rhythms).
Here, we offer a behind-the-scenes look at how the study came together, what we measured, and why it represents a major step forward for both sleep science and Eight Sleep.
We ran this study to investigate how temperature regulation impacts sleep during menopause
By 2030, it is estimated that 14% of the global population will be menopausal, yet the impact of menopause on sleep and overnight physiology remains poorly understood. Most prior research relies on short protocols run in sleep labs or young study populations, offering limited insight into what actually happens during sleep at home and during midlife. Also, overnight temperature regulation (either the participants’ skin and body temperatures or bed temperature) is not a commonly studied variable. Since temperature regulation is a core capability of the Eight Sleep Pod, we designed a study to investigate:
- How nighttime body and skin temperatures change with age
- How those changes affect sleep quality and cardiovascular recovery
- Whether actively regulating bed temperature can meaningfully change underlying physiology
We ran a controlled, at-home study
From July to October 2025, Eight Sleep Labs conducted a controlled, at-home study involving 90 participants (average age was 56 years):
- 60 postmenopausal women (half using hormone replacement therapy and half not)
- 30 men of a similar age
Participants slept with Pod temperature regulation OFF for one week and ON for one week, allowing each person to serve as their own control. This design made it possible to isolate the physiological impact of temperature regulation on sleep. This study is unique in the depth and continuity of data collected from over one-thousand nights.
What we measured (and why it matters)
To capture a complete picture of sleep and health, we combined multiple streams of physiological data into a single dataset:
- Sleep metrics: measured using both the Eight Sleep Pod and a biometric smart ring (Oura)
- Core body temperature: tracked continuously using an ingestible capsule
- Skin temperature: measured from multiple body sites overnight
- Circadian rhythm: derived from day and night core body temperature patterns
- Cardiovascular recovery: including heart rate and heart rate variability
- Glucose: tracked continuously day and night
- Hormones: urine measurements of estrogen, progesterone, luteinizing hormone, and follicle stimulating hormone
- Hydration: reported based on morning urine color
- Cognition: measured via validated, morning cognitive tests
In total, this single study generated:
- Over 10,700 hours of sleep data from 1,485 nights
- More than 577,000 core body temperature measurements
- More than 364,400 skin temperature data points and 119,300 glucose measurements
- Thousands of surveys capturing subjective sleep and menopausal symptoms
What we learned from these data
Analysis of this dataset revealed several important findings:
- The Pod reduces core temperature, which helps your heart recover overnight.
- The Pod helps restore the natural circadian rhythm that diminishes with age, where your core body temperature lowers early in the night and rises later in the night until you wake up.
- Without the Pod, eating and exercising near bedtime can have harmful cardiovascular impacts (higher sleeping heart rate and lower heart rate variability) for both postmenopausal women and age-matched men; however, the Pod helped to minimize these negative effects.
- We updated Hot Flash Mode to help you cool down quickly and fall back asleep comfortably after experiencing a nighttime hot flash.
We shared our findings with the greater scientific community
This study has resulted in two scientific manuscripts submitted for peer-review, both of which are currently available via preprint:
- Active temperature regulation improves nocturnal hot flashes and sleep in menopausal women (preprint): This paper examines how sleeping on the Pod reduces nighttime hot flashes by 56% on average and improves perceived sleep quality in menopausal women.
- Overnight temperature regulation restores core body temperature rhythms and improves cardiovascular recovery (preprint): This paper focuses on how the Pod helps restore the circadian rhythm of core body temperature and improves overnight cardiovascular recovery in postmenopausal women and men of a similar age.
Importantly, both papers are grounded in longitudinal data collected from more than one-thousand nights, rather than short laboratory snapshots. This is important because it allows us to make sleep research more accessible and applicable to the real-world and especially to populations that have previously been understudied.
We did this massive effort with a small team
A study of this size and scope would typically require a large research group. At Eight Sleep Labs, it was executed by a focused team of three: one research associate managing day-to-day study operations, one data engineer building and maintaining the data pipeline, and one data scientist translating raw data into meaningful insights.
Eight Sleep will integrate these findings into future products and features
This study represents more than a single research milestone. It marks a shift in how we generate evidence. Our Women’s Sleep Initiative is pushing the frontiers of sleep research by studying continuous, real-world physiology in historically understudied populations to inform product decisions, new features, and expand scientific understanding. The best part is that this is just the beginning.
