Effect of amantadine on the sleep-wake cycle of an inpatient with brain injury

Background: A previous study suggested that the routine use of drugs intended to improve attention and arousal, such as methylphenidate, tend to have a variable but not significant effect on sleep-wake cycles. As amantadine is a frequently employed drug in brain injury rehabilitation, with known effects on fatigue and motor processing speed, this study examined the effect of amantadine on the sleep-wake behaviour of patients with brain injury undergoing rehabilitation. Method: This was a naturalistic observation using an observationally defined sleep-wake distribution for a total of 43 subjects with brain injury. Identified patients were observed for a full 24 hours a day 2 weeks before and 2 weeks after starting amantadine. Some of these patients (n = 12) had been administered amantadine on clinical grounds and, for this paper, served as the experimental group, while the drug naive (n = 31) served as a control. Three outcome measures were operationalized: hours of sleep in 24 hours, hours of sleep during daytime and hours of sleep during night-time. Result: The average number of hours of sleep during a 24-hour period was not significantly different for the two cohorts. Similarly hours of sleep during daytime and hours of sleep during night-time were on average the same for the two groups. The data suggest that amantadine has no direct bearing on sleep/wake cycles using these parameters. Conclusion: This study fails to demonstrate that the use of amantadine on an inpatient brain injury population will affect sleep/wake quantity.