Theanine is an amino acid derived from green tea that supports relaxation.  A Japanese study on healthy volunteers which had participants wearing sleep monitoring devices reported that, while Theanine did not give them more sleep in the same period of time, they did get deeper, more restful sleep. 

5-HTP (5 Hydroxytryptophan) is made from the seed pods of Griffonia simplicifoliais , 5-HTP is a naturally occurring amino acid tryptophan.  Biochemically, it is a precursor to the neurotransmitter serotonin and eventually, melatonin.  Studies have shown it can help reestablish healthy sleep habits.

β-phenyl-γ-aminobutyric acid is a GABA derivative which crosses the blood brain barrier and assists in relaxation.

Melatonin is a sleep hormone produced by the pineal gland in the brain and helps control your sleep cycle.  It is a vital part of the bodies circadian rhythm.