1. Sleep inducing
   - soporific, somniferous, somnific, hypnogogic, hypnagogic 
2. Inducing mental lethargy
   - narcotic, soporific

See also: depressant, uninteresting

• overexert
• overexert oneself
• overexertion
• overexploit
• overexploitation
• overexpose
• overexposure
• overextend
• overfamiliar
• overfamiliarity
• overfatigue
• overfed
• overfeed
• overfeeding
• overfill
• overfish
• overflight
• overflow
• overflow incontinence
• overflowing
• overfly
• overfond
• overfull
• overgarment
• overgeneralise