Figure 4:

Muscle sympathetic nerve (MSNA) reactivity to the cold pressor test in healthy adults and individuals with chronic insomnia. Individuals with chronic insomnia showed augmented total MSNA reactivity to cold pressor stress (A). This is similarly depicted in the representative neurogram (B) showing healthy controls (B, Top) and individuals with chronic insomnia (B, bottom) during resting baseline and a 2-minute cold pressor test. The dotted lines (B) represent amplitude normalization to the largest sympathetic burst during baseline recording. MSNA, muscle sympathetic nerve activity. Obtained with permission from Carter et al.¹⁰