General sleepiness:
* Sleepily: This is the most direct adverb, meaning "in a sleepy way".
* Drowsily: Similar to "sleepily", but emphasizes a slow and languid feeling.
* Wearily: Suggests tiredness and exhaustion, often due to lack of sleep.
Extreme sleepiness:
* Exhaustedly: Indicates severe fatigue and a strong desire to sleep.
* Stuporously: Implies a state of near-unconsciousness due to extreme sleepiness.
Specific actions:
* Yawningly: Describes an action done while yawning due to sleepiness.
* Lazily: Implies a lack of energy and motivation due to sleepiness.
Ultimately, the best adverb depends on the specific context and the effect you want to achieve.