In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: CONCLUSIONS : Morning - dosed modafinil promotes nocturnal sleep , normalizes sleep architecture , and decreases daytime sleepiness in abstinent cocaine users .
### Output Text:
CONCLUSIONS : Morning - dosed <span class="chemical">modafinil</span> promotes nocturnal sleep , normalizes sleep architecture , and decreases daytime sleepiness in abstinent <span class="chemical">cocaine</span> users . 