Naps and modafinil as countermeasures for the effects of sleep deprivation on cognitive performance.

Disruptions in wake-sleep rhythms, particularly induced by sleep deprivation are limiting factors for military personnel in operations. The role of sleep and naps in the recovery of performance is generally accepted. Pharmacological aids, for example hypnotic or stimulant substances can also be effective countermeasures. Recently, a new stimulant compound, modafinil (MODIODAL) has also proven effective. Considering the excellent results obtained with napping and modafinil, we have studied the combined effect of these two countermeasures on psychomotor performance under conditions simulating an operational situation. Beneficial effects of a few hours' nap on performance were confirmed. Consequently naps should be encouraged, even if limited and diurnal. Modafinil, which combines wakening and stimulating properties without any known side effects, was useful for longer periods of sleep deprivation and when there was no real possibility of sleep recovery. Modafinil did not prevent sleep if sleep opportunities were available. The combination of naps and modafinil demonstrated the best cognitive performance during sleep deprivation.