Evaluation of motor behavior and sleep/wake pattern in depressed patients by wrist-actigraphy

A.C. Volkers1,2, J.H.M. Tulen1, W.W. van den Broek1, J. Bruyn1, J. Passchier2 and L. Pepplinkhuizen1

1Department of Psychiatry, University Hospital Rotterdam - Dijkzigt and Erasmus University Rotterdam, Rotterdam, The Netherlands
2 Department of Medical Psychology & Psychotherapy, University Hospital Rotterdam - Dijkzigt and Erasmus University Rotterdam, Rotterdam, The Netherlands

Alterations in psychomotor behavior and sleep/wake pattern are characteristic features of a major depressive disorder. To evaluate these features, wrist-actigraphy can be applied as a method to assess 24-hour patterns of spontaneous motor activity for prolonged periods of time in a natural environment.

In this study, wrist-actigraphy in combination with sleep logs was utilized to evaluate in severely depressed patients disturbances in motor activity levels (retardation), sleep latency, sleep duration and motor activity characteristics of the sleep period.

Participants were 71 depressed patients (26 males and 45 females, mean age= 52.7, sd=8.7) and 96 healthy subjects (51 males and 45 females, mean age=41.2, sd=8.7). The patients were free of psychopharmaca for at least one week and had a mean score on the Hamilton Rating Scale of Depression of 27.7 (sd=5.0). The healthy subjects were medication-free for at least three months prior to the study, they were not under any medical treatment and had no personal history of psychiatric illness. Motor activity was monitored by a wrist-actigraph (Gaehwiler Electronic) which contains a piezoelectric accelerometer (sensitive to 0.1 g and above) that records both intensity and frequency of movements per 30 second. The actigraph was continuously worn on the non-dominant wrist for 3 consecutive 24-hour periods. In addition, a sleep log was kept in which participants recorded their sleep/wake times, sleep latency time and the periods the actigraph was taken off.

Table 1 shows, for patients and healthy subjects separately, the motor activity levels during wake (Act. W) and sleep (Act. S), the total wake and sleep time (TWT and TST, respectively), sleep latency time (SLT) and the immobility indeduring the sleep period (Imm. S). Differences between patients and healthy subjects were studied by t-tests or non-parametric Mann-Whitney U-tests, dependent on the distribution of data.

Table 1. Mean (sd) motor activity and sleep parameters.

  Patients Controls Difference P
Act. W (movements / 30s) 17.7 (8.9) 30.4 (12.7) -12.7 <0.01
Act. S (movements / 30s) 18.5 (1.5) 1.3 (0.8) 0.5 ns
TWT (min) 848.5 (60.8) 944.7 (58.4) -96.2 <.001
TST (min) 375.1 (95.5) 420.6 (51.5) 45.5 <.01
SLT (min) 72.4 (44.3) 22.8 (21.5) 49.6 <.001
Imm. S 0.91 (0.06) 0.92 (0.03) 0.01 ns

Depressed patients were found to be significantly less active during wake than healthy subjects, but no difference in motor activity level was observed during the sleep period. Both total wake and sleep time were significantly decreased in the patient group. Additionally, the patients demonstrated a significantly larger sleep latency time than healthy subjects. No alteration was observed in depressed patients regarding the immobility index during the sleep period.

Our findings underline the presence of disturbances in motor activity during daytime (psychomotor retardation) and sleep patterns in depressed patients.

In future actigraphy research, we will focus on the clinical relevance of wrist-actigraphy as a useful tool to evaluate treatment effectiveness and to predict treatment response in this patient group.

Poster presented at Measuring Behavior 2000, 3rd International Conference on Methods and Techniques in Behavioral Research, 15-18 August 2000, Nijmegen, The Netherlands

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