MOTION AND SLEEP: NEUROPSYCHOLOGY AND BIOMARKERS

Mobility or "self-motion" is fundamental for adaptation and survival in 3D visual and gravitational worlds where "optic flow" provides dominant information. Normal information from vestibular and kinesthetic systems must be integrated to provide a common neural framework for self-motion. Conflicting sensory-motor conditions may rearrange normal relations among visual, vestibular, and kinesthetic cues. In moving environments, susceptible subjects may experience motion sickness or illusory self-motion, with cognitive performance disturbances. Pineal melatonin modulates sleep-wake cycles, drowsiness, mood, and cognitive performance. Sleep may be altered by vestibular stimulation changes in space sickness through relationships with the sopite syndrome, sometimes the sole motion sickness manifestation. Pituitary ACTH and adrenal cortisol regulate level of arousal, stress, and motion sickness susceptibility. Changes in cognitive performance and neurohormones occur in self-motion and in motion sickness. The aims of this proposal are to: expose young male and female adults to an optic display in a rotating optokinetic nystagmus drum to produce circular vection (CV) and symptoms of the sopite syndrome (SSS), and to determine whether small doses [0 or 3 mg] of oral (sublingual) melatonin can affect levels of endogenous salivary melatonin and cortisol, or increase the incidence, latency, and severity of CV and SSS.