What are the uses for l-tyrosine and 5-htp?

Alertness, and Sleep: L-tyrosine is a stimulatory neurotransmitter precursor. 5htp is an inhibitory neurotransmitter precursor. Both may be helpful as antidepressants when appropriately used. L-tyrosine is best taken in the morning or during the day; 5htp is best taken (in high doses--150 mg) at bedtime, or lower doses (50 mg) during the day.