0095 Magnitude of Temperature Drop Prior to Sleep Onset May Predict Increase in Slow Wave Sleep

Abstract

Abstract Introduction Neural circuitry implicated in thermoregulation is known to be interdependent with that implicated in regulation of sleep-wake state. In addition, previous studies in both rodent and human have shown that the sleep-associated decline in core body temperature (CBT) is associated with subsequent slow wave sleep. We sought to replicate this association in cognitively normal older adults, and extend upon previous studies by using automated telemetric methods to measure CBT. Methods Thirty-one cognitively normal and mildly cognitively impaired (MCI) older adults (age 68 ± 6 years, 18 female, 3 MCI) underwent measurement of CBT for two consecutive nights with a telemetric sensor, during which lab nocturnal polysomnography was simultaneously performed. Data from the second night were used. A validated algorithm was used to preprocess CBT to exclude and fill artifactual data outliers and small gaps, respectively. The sleep-associated CBT was calculated with an automated procedure by identifying the CBT decrease between the first peak in CBT identified prior to ‘Lights Out’ and the lowest value following Lights Out. Slow wave activity (SWA) increase was calculated as increase relative to baseline in the relative spectral power (0.5-4.0 Hz, F3-M2) in the first 5 second epoch following lights out. Results Of the 31 participants, 21 had both good quality EEG and CBT data, with an average total sleep time of 7.5 ± 1.5 hours, and an average duration 46.6 ± 18.5 hours of CBT data collected. There was a strong positive correlation between the magnitude of CBT decline and subsequent SWA (rho = 0.70, p < 0.001 Spearman’s Rank correlation), supporting previous results. Conclusion This is one of the first studies to obtain simultaneous CBT and NPSG data in older adults using an ingestible telemetric sensor. Our results support the previous research that there is a significant relationship between sleep-associated body cooling prior to sleep onset and increase in SWA. This highlights the potential for future therapeutic thermal intervention in older adults to improve sleep and sleep mediated health conditions. Further research with a bigger sample size will be necessary to control for variables such as obstructive sleep apnea and cognition status. Support (if any) NIH R01AG070866, R21AG055002, K25HL151912,