(S (S (NP (BASENP (DT The) (NN analysis)) (PRN (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBD included) (BASENP (NN 17) (JJ peer-reviewed) (JJ scientific) (NNS papers))))) (COMMA ,))) (VP (VBD was) (VP (VBN aimed) (PP (IN at) (S (VP (VBG determining) (SBAR (IN whether) (S (NP (BASENP (NNS supplements)) (PP (IN of) (BASENP (DT the) (NN hormone)))) (VP (MD can) (VP (VP (VB improve) (BASENP (NN sleep))) (PP (IN among) (NP (NP (BASENP (NNS insomniacs)) (COMMA ,) (BASENP (JJR older) (NNS adults))) (CC and) (BASENP (NNS others)))))))))))))) (PERIOD .))