Fig. 2
From: Autonomic regulation across sleep and wake during an Antarctic overwintering
Amplitude of the circadian HRV rhythm throughout one year of Antarctic isolation. Shown are observed means with 95% confidence intervals (vertical bars); lines connect the means across time. The curves show the model-predicted trends based on the linear mixed models (LMMs), with shaded areas representing 95% confidence intervals. ‘Amp’ stands for the amplitude of the cosinor curve fitted to each HRV variable. RRM, average duration of RR intervals in milliseconds; SDNN, standard deviation of RR intervals in milliseconds; RMSSD, root mean square of successive RR interval differences; VLF, very low-frequency component; LF, low-frequency component; HF, high-frequency component; HFnu, normalized units of HF; LH, HF/LF ratio.
