Duration: February – July 2013


Measuring sleep disorders is of scientific and clinical interest to make statements about its causes and consequences. Polysomnography, actigraphy and subjective self-report are most frequently used to measure sleep quality. A recently developed device to measure sleep quality is the ZEO sleep management system (Zeo, Inc., Newton, MA, USA).


In this study utility and validity of the ZEO was investigated.


Participants were recruited from the Hanze University of Applied Sciences (UAS) Groningen, the Interdisciplinary Center for Psychopathology and Emotion regulation (ICPE) and the University Center of Psychiatry (UCP) Groningen. The participants in the study for ZEO’s utility were the same as for the validity study, supplemented with 3rd year students from the Hanze UAS who used the ZEO for a school project.

To measure the utility of the ZEO, a questionnaire asking for positive and negative aspects of using the ZEO, the influence of using the device on sleep quality and suggestions for improvement of the device was used. Also participants were asked to rate the ZEO with a mark between 1 and 10, where 1 means very bad utility and 10 means excellent utility.

The Pittsburgh Sleep Diary, used as golden standard, is a questionnaire containing eleven closed-answer questions about the amount of times someone woke up during the night, the time it took to fall asleep, sleep quality and mood.


In this study 8 females and 3 males took part with mean (SD) age 30 (9.9) years.   Mean (SD) amount of nights slept with the ZEO headband was 20 (13.57). Positive remarks were: “interesting to measure sleep” and “easy to use”. Reported disadvantages were: headband did not stay in  place or fell off (n=8), could be thinner and was so tight that it left marks and skin irritations, malfunctioning (n=4), website could be improved, more wake ups (n=7). The ZEO was rated with a grade of 6.91 (SD= .94) on a scale from 1 to 10.

Eight participants started the validation study, two dropped out after a few nights. Due to problems with the website, in two participants only 36 and 39 nights with ZEO could be analyzed, instead of 50.

For sleep quality, absolute agreement between ZEO scores and Pittsburgh Sleep Diary results (ICC’s) ranged from .04-.48 with a statistically significant difference in 5 out of 6 participants. For total sleep time the ICC’s were .29-.73 with two statistically significant differences. ICC’s for time to fall asleep were .02-.41, with half of the participants showing a statistically significant difference between ZEO and sleep diary. Amount of awakenings showed ICC’s between -.01-.15, all but one were significantly different. Duration of awakenings showed slightly better results with only two statistically significant differences and ICC’s between .06-.62. The moment of falling asleep showed four statistically significant differences and moderate to high ICC’s (.68-1.00). The end of night moment had three statistically significant differences and strong correlations (ICC’s .88-.97).

ARIMA analyses showed variances per variable and per participant. No systematic differences were found between the two methods of measurement.


The utility of the ZEO sleep manager was judged ‘sufficient’, with the lack of comfort of the headband as a major disadvantage. A strong absolute agreement between the ZEO sleep management system (Zeo, Inc., Newton, MA, USA) and the Pittsburgh Sleep Diary was found for sleep time and wake time. No significant systematic differences were found between the two methods, but some trends were identified. After at least two weeks of wearing the ZEO eleven healthy adults rated its’ utility. Six of the participants used the device for 50 consecutive nights and also filled in the Pittsburgh Sleep Diary.


This study is described in a thesis for the Bachelor in Psychology at the University of Groningen.