Figure 3 : Effect of secondary injection of 5-hydroxytryptophan during
insomnia produced by p-chlorophenylalanine in the cat
(Top two lines) Normal pattern of sleep in a cat for which electroencephalographic
recordings were made over a long period. (Bottom five lines) Total insomnia
96 hours after the last of three daily injections of p-chloro phenylalanine
(400 milligrams per kilogram), then, following the injection (see arrow)
of 5-hydroxytryptophan (5 milligrams per kilogram), reappearance of the
normal pat tern of sleep. Insomnia returns 8 hours after the injection.
(Base line of each record) Waking; (white rectangles) slow-wave sleep:
(black rectangles) paradoxical sleep.