Sopite symptoms in the optokinetic drum.

UNLABELLED: Sopite syndrome is a disturbance caused by motion characterized by drowsiness and mood changes that may occur without the classic symptoms of motion sickness. Because sopite symptoms are often subtle, it is important to assess for their presence, and to distinguish true sopite symptoms from changes in mood and drowsiness that are due to non-motion related factors such as fatigue and boredom. We compared sopite symptoms in the optokinetic drum (OKD) with symptoms in a control condition in which the drum's motion cues were removed.

METHODS: There were 48 Introductory Psychology students who were randomly assigned to 1 of 2 groups: the rotating stripes group (RS) sat inside a drum lined with black and white stripes. The drum rotated at 5 rpm. The control group (Ctrl) sat inside the same drum without stripes or rotation. All participants completed the Positive and Negative Affect Scale (PANAS), the Motion Sickness Assessment Questionnaire (MSAQ), and the Epworth Sleepiness Scale (ESS) at pre- and post-drum exposures.

RESULTS: The RS, but not the Ctrl, showed increases on all four MSAQ subscales (gastric, peripheral, central, sopite). The groups showed equivalent decreases in positive and negative affect. These findings show that some sopite-related symptoms were due specifically to the motion stimuli, while others could be attributed to non-motion aspects of the experimental situation.

DISCUSSION: The findings have implications for the use of control conditions in the study of sopite syndrome, and for methods of assessing the changes in mood and drowsiness that are the cardinal symptoms of sopite.