Sympathetic Nervous System Effects on End Organ Blood Flow and Vascular Resistance in the Eye

In sleep, there are bursts of sympathetic nerve activity. We aimed to characterize changes in blood flow and vascular resistance in the eye due to these bursts. While blood flow to the eye cannot be measured during sleep, the effect of sympathetic nerve activity can be studied in the awake state using cold water immersion. We also examined if changes in the eye due to sympathetic nerve activity correlated to changes in finger pulse amplitude which can be monitored during sleep non-invasively with a wearable device.