How accurate is the sleep data from the Zeo?

Research & Education

The Zeo Sleep Research Center of Zeo, Inc, is dedicated to promoting sleep research and education and Advancing Science in Support of Sleep Fitness™. With a world-class Scientific Advisory Board and a mission to educate and empower people through the power of sleep, we endeavor to develop and support products and services with the utmost integrity. Zeo’s SoftWave™ technology has been validated in research settings. Ongoing validations and use of our technology in research and education will ensure that we remain well grounded in science.

We look forward to continuing to work with others who wish to share the power of sleep through research and education.

Scientific Advisory Board
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Zeo’s Scientific Advisory Board includes thought leaders from sleep medicine, sleep science, and behavioral psychology. The Board actively guides and advises Zeo and enthusiastically shares our mission to better educate consumers about the critical importance of a better night’s sleep.

  • Chair: Kenneth P. Wright Jr., PhDDirector, Sleep and Chronobiology Lab
    University of Colorado, Boulder
  • Daniel Aeschbach, PhDAssistant Professor of Medicine
    Harvard Medical School
  • Michael J. Breus, PhD“The Sleep Doctor,” author, WebMD® sleep expert and AOL® wellness coach
  • Charles A. Czeisler, PhD, MDDirector, Division of Sleep Medicine
    Harvard Medical School
  • Phyllis C. Zee, MD, PhDProfessor of Neurology, Neurobiology and Physiology
    Director, Sleep Disorders Center
    Northwestern University Medical School
  • John W. Winkelman, MD, PhDAssistant Professor of Psychiatry
    Harvard Medical School
    Medical Director, Sleep Health Center
    Brigham and Women’s Hospital

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Zeo’s SoftWave technology has been validated in two scientifically controlled studies by comparing it with full in-lab polysomnography, which experts consider to be the gold-standard for measuring sleep.

The aim of these IRB-approved studies was to demonstrate that the technology used in the Zeo Personal Sleep Coach is reliable and accurate. Download the available poster presentations, or go to the published materials through the links below.

Download scientific presentations here:

  •  Wright K, Johnstone J, Fabregas SE, Shambroom JR. Evaluation of a Portable, Dry Sensor-Based Automatic Sleep Monitoring System. Sleep. 2008;31 (Suppl.):A337. Abstract 1023. [Download Poster] [Download Abstract]SoftWave agreement with each of the two experts at any instant in time was similar to agreement the agreement between the two experts.
  •  Wright K, Johnstone J, Fabregas SE, Shambroom JR. Assessment of Dry Headband Technology for
    Automatic Sleep Monitoring. Journal of Sleep Research. 2008;17 Suppl.1:230. Abstract P428. [Download Poster] [Download Abstract]
    Sleep summary measures were consistent between SoftWave and each of the two experts.
  •  Fabregas SE, Johnstone J, Shambroom JR. Performance of a Wireless Dry Sensor System in Automatically Monitoring Sleep and Wakefulness. Sleep. 2009;32 (Suppl.):A388. Abstract 1189.  [Download Poster] [Download Abstract]The SoftWave technology was able to differentiate sleep and wake at least as well as actigraphy and comparably to the two experts.
  •  Shambroom JR, Johnstone J, Fabregas SE. Evaluation of Portable Monitor
    for Sleep Staging. Sleep. 2009;32 (Suppl.):A386. Abstract 1182. [Download Poster] [Download Abstract]
    Sleep summary measures were consistent between Softwave, actigraphy, and the two experts.

Blake SK, Pittman SD, MacDonald MM, et al. Assessment of a wireless dry sensor to detect sleep in healthy volunteers and subjects with sleep disorders. Sleep. 2009;32 (Suppl.):A370. Abstract 1132. [Download Abstract]

Zeo Home Use Test

Prior to launching Zeo we conducted a test of home users of the Zeo Personal Sleep Coach. While this study did not include a scientific control group, Zeo users reported significant improvements in the quality of their sleep and better functioning in the daytime.
Download the full report [PDF]

Research & Education
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Many scientists and educators have already found uses for Zeo and SoftWave technology in research projects and in the classroom. Some of the resulting research has been published:

  • Drake C, Gumenyuk V, Jefferson C, Kick A, Coaker M, Roth T. Extending time in bed in short sleepers: effects on objective sleep parameters measured in the home. Sleep 2010;33 (Suppl.):A113. Abstract 0322. [Download Abstract]
  • Drake C, Jefferson C, Kick A, Roth T. The effects of caffeine given 0, 3, or 6 hours before bed on objective sleep parameters measured in the home. Sleep 2010;33 (Suppl.):A107. Abstract 0306. [Download Abstract]

Two abstracts from Chris Drake’s group at the Henry Ford Hospital in Michigan report on novel data that indicate that ZQ (Zeo’s single number summary of a night of sleep) is sensitive to the positive effects of sleep extension, as well as the negative effects of caffeine use close to bedtime. Both abstracts have been accepted for oral presentation in June 2010 at the 24th Annual Meeting of the Associated Professional Sleep Societies.

  • Maas JB, Fabregas SE, Kopynec RM, Haswell DR, Fortgang RG, Shambroom J. Putting sleep to the test: a collegiate sleep study. Sleep 2010;33 (Suppl.):A77. Astract 0221. [Download Abstract]

As a part of the largest objective measurement study of student sleep in their home environments, these data (from Cornell University) show the poer of using objective measurements for sleep in addition to a sleep habits focused intervention for increasing total sleep time in a student population. This abstract has been accepted for a poster presentation in June 2010 at the 24th Annual Meeting of the Associated Profesional Sleep Societies.

In addition to these research studies, Zeo has been used for education in college and university classrooms such as Brown University in Providence, RI, and Stonehill College in Easton, MA.

Inquiries and Support
We recognize the incredible importance of researchers and educators, and also the challenges that they face in continuing their work. In order to do our part, we often support and provide special pricing for vital research and education efforts.

If you are interested in using Zeo or SoftWave technology in your research or in the classroom, please contact us at Although we cannot accommodate all requests, we will carefully consider every inquiry.

Our Pledge to You

We pledge to the health and wellness professionals that we will continuously:

  • Review: Rigorously review current and future products and services with our Scientific Advisory Board and other respected members of the scientific community.
  • Validate: Ensure that our services and technologies are based on well-studied practices, adapted for the consumer marketplace, and are scientifically validated.
  • Support: Pursue our passionate commitment to scientific knowledge by identifying and supporting promising sleep research and education initiatives to cultivate novel discoveries and empower people to oimprove their lives through sleep.


The two studies cited on the validation page (the first study was funded by Zeo, the second was not) had the following results:

Study 1 (funded by Zeo and performed partly by Zeo staff): Shambroom JR, Fabregas SE, Johnstone J. Validation of an automated wireless system to monitor sleep in healthy adults. J Sleep Res. Published online ahead of print August 21, 2011

The WS [Wireless System/Zeo] agreement with each of the two PSG [polysomnography] scores for sleep stages was 75.8 and 74.7%, respectively. WS agreement with each of the two PSG scores for sleep/wakefulness was 92.6 and 91.1%, ACT [wrist motion sensor] agreement with PSG was 86.3 and 85.7%. The PSG scorers’ agreement with each other for sleep stages was 83.2%, and for sleep/wakefulness was 95.8%. The findings from the current study indicate that the WS may provide an easy to use and accurate complement to other established technologies for measuring sleep in healthy adults.
Study 2 (not funded by Zeo): Blake SK, Pittman SD, MacDonald MM, et al. Assessment of a wireless dry sensor to detect sleep in healthy volunteers and subjects with sleep disorders. Sleep. 2009;32 (Suppl.):A370. Abstract 1132.

PSG and WS data were available for 29 subjects [10 healthy, 10 obstructive sleep apnea, 10 insomniacs — one disordered subject dropped] for a total of 24,138 epochs. Sleep staging (all subjects) agreements/κ [kappa — inter-rater reliability] were: WS-M1 [M1: one of the PSG markers/evaluators]: 68%/0.50, WS-M2 [M2: another marker/evaluator]: 68%/0.48, M1-M2: 88%/0.79. Sleep staging (healthy volunteers, n=10) agreements/κ were WS-M1: 73%/0.58, WS-M2: 72%/0.51, M1-M2: 89%/0.81. Sleep staging (sleep disordered subjects, n=19) agreements/κ were WS-M1: 65%/0.45, WS-M2: 66%/0.44, M1-M2: 88%/0.81. Mean LPSs [Latency to Persistent Sleep measurements — i.e., time to get to sleep] (all subjects) were WS: 15±14, M1: 48±83, M2: 48±84 minutes. Mean TSTs [Total Sleep Time] (all subjects) were WS: 349±76, M1: 331±84 and M2 329±89 minutes. Mean SEs [Sleep Efficiency — time_asleep/time_in_bed] (all subjects) were WS: 86±17%, M1: 79±19% and M2: 79±20%
Take home message: Going just with the most conservative result above, for healthy people the Zeo is reasonably accurate, performing at about 72.5%/89% = 81% of the best possible performance. It seems likely that the Zeo incorporates an assumption that the user does not have a sleep disorder, because although it was more accurate on the healthy volunteers, it significantly underestimates the time required to get to sleep and overestimates total sleep time and sleep efficiency (across all subjects). So, if you do not have a sleep disorder, the Zeo might be slightly overestimating how much sleep you’re getting. If you do have a sleep disorder, the Zeo might significantly overestimate the quality and quantity of your sleep.

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