Possible Clues:

• Addictive drug
• Drug
• Drug producing numbness or stupor
• Soporific drug
• Drug that induces sleep
• Hurried back to bed with current cold, as it might help one to sleep
• Is not entertaining brief part on The Bridge - the one caught with the drug
• Drug causing sleep or drowsiness
• Drug producing numbness and stupor
• Drug that induces drowsiness or stupor