Figure 2 : Effects of p-chlorophenylalanine on sleep and brain concentrations of serotonin in the rat

After intraperitoneal injection (500 milligrams per kilogram), there is a decrease in the amount of slow wave sleep (SWS) and in serotonin (5 HT) concentration, followed by a slow return to normal values after 268 hours.

(Solid line) Percentage of slow-wave sleep relative to the amount for a control rat; each point represents the mean percentage per 12-hour period (black dots at top in dicate night hours, 7 p.m. to 7 a.m. ) .

(Dashed line) Percentage of serotonin (relative to the concentration for a control rat); for the purpose of this analysis, two animals were killed every 12 hours.

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