Association between skin temperature and actigraphic sleep metrics in patients with Parkinson's disease: The PHASE study

• We examined associations between nighttime skin temperature (ST) and sleep quality. • Nighttime ST was lower in patients with Parkinson's disease (PD). • There were interactions between nighttime ST and PD for various sleep measurements. • Within-individual changes in nighttime ST were linked to actigraphic sleep changes. • Enhancing heat dissipation may improve sleep quality in patients with PD. Introduction Sleep initiation and maintenance are linked to thermoregulation. In Parkinson's disease (PD), thermoregulatory dysfunction potentially worsens sleep disorders. However, the association between thermoregulation and sleep quality in patients with PD remains unclear. We aimed to examine the association between skin temperature, a measure of heat dissipation, and actigraphic sleep metrics in PD. Methods In this cross-sectional study with 186 outpatients with PD and 580 non-PD controls, we measured wrist skin temperature (WST) and actigraphic sleep quality for seven days in PD and two days in controls in real-life settings. Linear mixed-effect models were used to examine the association between nighttime WST and sleep quality. Results Nighttime WST in PD was significantly lower than that in controls (adjusted difference 0.39 [95 % confidence interval, 0.23–0.54] °C, P < 0.001). In patients with PD, changes in sleep efficiency, wake after sleep onset, total sleep time, and log-transformed fragmentation index per 1 °C increase in nighttime WST were 3.2 (95 % CI, 2.4–3.9) %, −10.3 (95 % CI, −13.6, −7.1) minutes, 13.4 (95 % CI, 9.1–17.8) minutes, and −0.09 (95 % CI: −0.12, −0.06), respectively, independent of potential confounders. Significant interactions were observed between nighttime WST and the presence of PD for sleep efficiency, wake after sleep onset, and total sleep time. Conclusions: Within-individual changes in nighttime WST were significantly associated with changes in actigraphic sleep measures in PD. Interventional studies are necessary that address the limitations and potential biases of this study to elucidate whether cutaneous temperature modulation can enhance the quality of sleep in PD.