The relationship between waking time and urinary epinephrine in bed-rested humans under conditions involving minimal stress.

The correlation between urinary excretion of epinephrine and percent of waking time during time allotted for sleep was evaluated for both daytime and nighttime bed-rest under minimally stressful conditions. The experiment was performed on 6 male subjects. Polysomnographic recordings were made throughout each 8-h bed-rest period, and free epinephrine excretion was measured at intervals of 2.5 h. Epinephrine excretion showed a strongly positive correlation with percent of waking time during bed-rest in the daytime and at night (average correlation coefficient: day: r = 0.89, P less than 0.001; night: r = 0.68, P less than 0.001). The possibility that levels of epinephrine excretion could be used as an indicator of sleep disturbance is discussed.