Psychophysiological Characteristics of Insomnia Patients Measured by Biofeedback System / 수면정신생리

ABSTRACT

BACKGROUND AND OBJECTIVES: Insomnia is the most prevalent sleep disorder in the general population and is considered to be a disorder of hyperarousal. The aim of this study was to measure the psychophysiological responses in insomnia patients using a biofeedback system, and to compare them with results from normal healthy subjects. MATERIALS AND MATHODS Eighty patients with primary insomnia (35 males and 45 females, average age 49.71 +/- 12.91 years) and 101 normal healthy controls (64 males and 37 females, average age 27.65 +/- 2.77) participated in this study. Electromyography (EMG), heart rate (HR), skin conductance (SC), skin temperature (ST), and respiratory rate (RR) were recorded using a biofeedback system during 5 phases (baseline, stress 1, recovery 1, stress 2, recovery 2) of a stress reactivity test, and average values were calculated. Difference in values between the two groups in each corresponding phase was analyzed with independent t-test, and change in values across phases of the stress reactivity test was analyzed with paired t-test (all two-tailed, p<0.05). RESULTS: Compared to normal controls, insomnia patients had higher EMG in all 5 phases (baseline 7.72 +/- 3.88 microV vs. 4.89 +/- 1.73 microV, t = -6.06, p<0.001 ; stress 1 10.29 +/- 5.16 microV vs. 6.63 +/- 2.48 microV, t = -5.84, p<0.001 ; recovery 1 7.87 +/- 3.86 microV vs. 5.17 +/- 2.17 microV, t = -5.61, p<0.001 ; stress 2 10.22 +/- 6.07 microV vs. 6.98 +/- 2.98 microV, t = -4.37, p<0.001 ; recovery 2 7.88 +/- 4.25 microV vs. 5.17 +/- 1.99 microV, t = -5.27, p<0.001). Change in heart rate across phases of the stress reactivity test were higher in normal controls than in insomnia patients (stress 1-baseline 6.48 +/- 0.59 vs. 3.77 +/- 0.59, t = 3.22, p = 0.002 ; recovery 1- stress 1 -5.36 +/- 0.0.59 vs. -3.16 +/- 0.47, t = 2.91, p = 0.004 ; stress 2-recovery 1 8.45 +/- 0.61 vs. 4.03 +/- 0.47, t = 5.72, p<0.001 ; recovery 2-stress 2 -8.56 +/- 0.65 vs. 4.02 +/- 0.51, t = -5.31, p<0.001). CONCLUSION: Psychophysiological profiles of insomnia patients in a stress reactivity test were different from those of normal healthy controls. These results suggest that the sympathetic nervous system is more highly activated in insomnia patients.