If you do something sleepily, you do it in a way that shows you are tired and want to sleep.
Doing something sleepily can make people think of being cozy and comfortable, but also a little slow or lazy.
Examples:
She yawned sleepily as she got into bed.
The cat blinked sleepily in the sun.
He walked sleepily to the kitchen for breakfast.
The baby looked at me sleepily and then closed his eyes.
The bear woke up sleepily from his long winter nap.
I tried to read a book, but I kept nodding off sleepily.