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Volume 15 No. 11
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Accepted Papers

Letters to the Editor

Non-Contact Sensors: Need for Optimum Information Is More Important Than Convenience

Mahadevappa Hunasikatti, MD, FCCP
Sleep Medicine Branch, Food and Drug Administration, Silver Spring, Maryland


Hunasikatti M. Non-contact sensors: need for optimum information is more important than convenience. J Clin Sleep Med. 2019;15(11):1707.

I read with interest the article by Schade et al.1 The authors show that sleep detection accuracy by S+V1 (93.3%), S+V2 (93.8%), and actigraphy (96.0%) was high and wake detection accuracy by each (69.6%, 73.1%, and 47.9%, respectively) was low. However, as shown in the study by Marino et al,2 specificity of actigraphy is low (0.329). In fact, many similar devices have high sensitivity and low specificity and thus it is uncertain how they may be incorporated into clinical use.

The sample size of 27 participants is too small to come to a definite conclusion regarding the sensitivity or specificity of the device. The combined light sleep, deep sleep, rapid eye movement sleep, and wake (four-stage) accuracy was not statistically significant to the extent that one can take clinical action in the management of sleep disorders. Another limitation of the study is that the sample comprised only healthy sleepers, so extrapolation to patients with clinical sleep disorders cannot be inferred.

Is there a need for such non-contact devices? Probably. There may be a better future for these devices if they can provide clinically relevant information (electroencephalography, airflow and photoplethysmography) with wireless sensors and minimal contact on the head. Because the consumer use of such devices currently is mostly unregulated, we need to be cautious about data provided by motion-based sensors. As this is already in the field of cardiology (patients bring single-lead electrocardiography results to the physician’s office with their own interpretations), sleep physicians are being asked questions for which the patients expect scientific explanation. Perhaps it is time for the American Academy of Sleep Medicine to assess new technology annually with recommendations.3

The race should be to provide useful, reliable information to patients and physicians, not to see how many fewer sensors can provide the information.


Dr. Hunasikatti is the sole author and approved the manuscript. The author reports no conflicts of interest. The opinion expressed are the personal views of the author and do not represent the opinion of FDA.



Schade MM, Bauer CE, Murray BR, et al. Sleep validity of a non-contact bedside movement and respiration-sensing device. J Clin Sleep Med. 2019;15(7):1051–1061. [PubMed]


Marino M, Li Y, Rueschman MN, et al. Measuring sleep: accuracy, sensitivity, and specificity of wrist actigraphy compared to polysomnography. Sleep. 2013;36(11):1747–1755. [PubMed Central][PubMed]


Khosla S, Deak MC, Gault D, et al. Consumer sleep technology: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2018;14(5):877–880. [PubMed Central][PubMed]