Effect of a chronic tryptophan dietary deficiency on the rat's sleep-wake cycle

The sleep-wake cycle of 12 tryptophan dietary deficient rats and their non-deficient paired controls were observed for a 8:00 a.m. to 8:00 p.m. period. EEG, EMG and body activity were continuously monitored on polygraphic recordings throughout the 12 hr observation period. The results indicate no significant difference between the tryptophan deficient and sufficient animals in time spent awake, slow-wave or parodoxical sleep. There was a non-significant trend among the tryptophan deficient animals to be less active and spend more time in both slow-wave and paradoxical sleep, which is in contrast to an expected insomnia effect. The results do not support the suggested relationship between reduced serotonin levels and the occurrence of insomnia, questioning the serotonergic theory of sleep.