Respiratory immunity responses and nocturnal sleeping quality alterations under thermoneutral environments: Does the siesta matter?

In order to explore the potential contributions of the siesta on nocturnal sleeping quality and respiratory immunity under thermoneutral environments, an experimental study was conducted under the thermoneutral environment. In this experiment, 20 subjects were recruited and divided into two groups, one of which had siesta while the other did not but acted as a control group. During the experiment at 25°C, the sleeping patterns, including the slow wave sleeping (SWS) duration, light sleeping (N1, N2 periods) duration, as well as the rapid eye movement (REM) duration, were recorded continuously. Meanwhile, the concentration of the salivary secretory immunoglobulin E (S-IgE), which acted as a biomarker of respiratory immunity, was also measured. Results showed that the mean skin temperature (MST) of the siesta group was 0.37°C lower than that of the control group. In addition, a slight increase (0.1°C) in core temperature was detected in the siesta group. Furthermore, results indicated that both the SWS and REM sleeping durations of the siesta group were reduced, while elevations were observed during the light sleeping duration. However, the subjective evaluation of the nocturnal sleeping quality of the siesta group was improved by 2.9 points. Finally, a higher S-IgE concentration was detected in the siesta group. This study revealed that the siesta might affect the nocturnal sleeping patterns; meanwhile, the changes in S-IgE might correspond to an improvement in respiratory immunity.