2606
OBJECTIVE : The purpose of the present study was to determine the effect of morning - dosed modafinil on sleep and daytime sleepiness in chronic cocaine users .
 modafinil, daytime sleepiness, cocaine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 modafinil, daytime sleepiness, cocaine