Circadian Phase Assessment of Core Body Temperature Using a Wearable Temperature Sensor Under the Real World
Naoko Kubota, Kazufumi Okada, Y. Yamanaka
Abstract
Abstract To evaluate whether a patch-type wearable temperature sensor (CALERA Research) could determine the circadian phase of core body temperature (CBT) in a manner like a rectal probe. Sixteen participants (27 ± 11 years, 8 males and 8 females) wore an actigraph and CALERA Research sensor on the chest region for 3–5 days in a real-world setting. Simultaneous rectal temperature measurements were performed during the nocturnal sleep period. The midpoints of the nocturnal decrease in CBT (CBTtrough) were used as the circadian phase marker. We analyzed 60 pairs of CBTtrough. The reliability and agreement of the CBTtrough from the two devices were analyzed using the intraclass correlation coefficient (ICC) and the concordance correlation coefficient (CCC). The Bland-Altman analysis was used to quantify the limit of agreement of CBTtrough between the devices. The ICC of 0.96 (95%CI: 0.93–0.98) and CCC of 0.96 (95%CI: 0.93–0.97) values indicated excellent reliability and substantial agreement, respectively. The mean bias was 0.16 hours (95%LoA: -0.76–1.07 hours). The mean CBTtrough comparison was 5.9 ± 1.6 hours in the CALERA Research sensor and 5.8 ± 1.7 hours in the rectal probe. The difference in the CBTtrough between the two devices was about ± 1.0 hour which would be an acceptable range for determining the CBTtrough. We suggest that the CALERA Research sensor could be a useful tool for reasonably estimating the circadian phase of CBTtrough and providing a surrogate for a rectal probe.