Dopey (adjective)

1. Sleepy, drowsy, or groggy, especially as a result of drug use.
2. Mentally slow or confused.

Origin:

Mid 19th century: from dope, a slang term for opium, + -y.

Examples:

1. He felt dopey after taking the sleeping pill.
2. She was dopey from staying up too late.
3. He was dopey after the long flight.
4. The medication made him dopey and he had trouble focusing.
5. He was dopey from the anesthesia and couldn't remember anything.