The most common and most likely answer to this crossword clue is the 9 letter word SLEEPIEST
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More clues leading to the result SLEEPIEST
Buddy explains!

The straight part
We know that "more tired than anyone else" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case more tired than anyone else = sleepiest.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SLEEPIEST mean?
SLEEPIEST adjective- Tired; feeling the need for sleep.
- Suggesting tiredness.
- Tending to induce sleep; soporific.
- Dull; lazy; heavy; sluggish.
- Quiet; without bustle or activity.