Injections of the serotonin precursor, 5-hydroxytryptophan,

A) reverse the insomnia produced in cats or rats by the serotonin antagonist PCPA.
B) reverse the sleep increases produced in mice by PCPA.
C) are effective in the treatment of human insomnia.
D) are effective in the treatment of human hypersomnia
E) reverse the increases in delta sleep produced in volunteers by sleep reduction.

Answer: A