Are essential oil diffusers safe to run overnight?

Most modern ultrasonic diffusers, including those in this roundup, include an auto-shutoff when water runs out, and reviewers commonly note sub-25 dB operation suitable for sleeping. That said, pediatricians and pet-owner communities caution against certain oils (tea tree, eucalyptus, peppermint) around infants and pets — check oil-specific guidance regardless of which diffuser you buy.