Df. Neri et al., THE EFFECTS OF TYROSINE ON COGNITIVE PERFORMANCE DURING EXTENDED WAKEFULNESS, Aviation, space, and environmental medicine, 66(4), 1995, pp. 313-319
Tyrosine, a large neutral amino acid found in dietary proteins, has re
ceived recent attention as a potential treatment for stress. The behav
ioral effects of tyrosine were examined during an episode of continuou
s nighttime work involving one night's sleep loss. Subjects performed
nine iterations of a battery of performance tasks and mood scales for
approximately 13 h, beginning at 1930 and ending at 0820. They remaine
d awake throughout the day on which the experiment began and were awak
e for more than 24 h by the end of testing. Six hours after the experi
ment began, one-half of the subjects received 150 mg . kg(-1) tyrosine
in a split dose while the other half received cornstarch placebo in a
double-blind procedure. Tyrosine administration was associated with a
significant amelioration of the usual performance decline on a psycho
motor task and a significant reduction in lapse probability on a high-
event-rate vigilance task. The improvements lasted on the order of 3 h
. The results of this study also suggest that tyrosine is a relatively
benign treatment at this dose. After further testing with other doses
and timing of administration, tyrosine may prove useful in counteract
ing performance decrements during episodes of sustained work coupled w
ith sleep loss.