title: The validity, reliability, and utility of the iButton® for measurement of body temperature circadian rhythms in sleep/wake research.
abstract: OBJECTIVE
  Changes in core body temperature due to heat transfer through the skin have a major influence on sleep regulation. Traditional measures of skin temperature are often complicated by extensive wiring and are not practical for use in normal living conditions. This review describes studies examining the reliability, validity and utility of the iButton®, a wireless peripheral thermometry device, in sleep/wake research.
  
  
  METHODS
  A review was conducted of English language literature on the iButton as a measure of circadian body temperature rhythms associated with the sleep/wake cycle.
  
  
  RESULTS
  Seven studies of the iButtton as a measure of human body temperature were included. The iButton was found to be a reliable and valid measure of body temperature. Its application to human skin was shown to be comfortable and tolerable with no significant adverse reactions. Distal skin temperatures were negatively correlated with sleep/wake activity, and the temperature gradient between the distal and proximal skin (DPG) was identified as an accurate physiological correlate of sleep propensity. Methodological issues included site of data logger placement, temperature masking factors, and temperature data analysis.
  
  
  CONCLUSIONS
  The iButton is an inexpensive, wireless data logger that can be used to obtain a valid measurement of human skin temperature. It is a practical alternative to traditional measures of circadian rhythms in sleep/wake research. Further research is needed to determine the utility of the iButton in vulnerable populations, including those with neurodegenerative disorders and memory impairment and pediatric populations.
authors.affiliation: University of Rochester, School of Nursing, 601 Elmwood Avenue, Rochester, NY 14642, USA. Michael_Hasselberg@urmc.rochester.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hasselberg
authors.forename: James
authors.initials: J
authors.lastname: McMahon
authors.forename: Kathy
authors.initials: K
authors.lastname: Parker
mesh_terms: D001831:Body Temperature / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D006801:Humans; D018670:Monitoring, Ambulatory / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D012890:Sleep / Q000502:physiology; D012893:Sleep Wake Disorders / Q000503:physiopathology