Me muero de sueño, estoy muerto de sueño

[ROBINDESBOIS]

In english?

[Rusty]

I'm dead.
I'm dead tired.
I can't keep my eyes open.
I'm exhausted.
I'm a pumpkin. (I'm turning orange. - may be very regional)

[pjt33]

I wouldn't understand "I'm a pumpkin."

I'm knackered (possibly Briticism).

[Rusty]

Briticism, indubitably.

Here are more American ways to say it:
I'm dying for sleep.
I'm dog tired.
I'm bushed.
I'm beat.

[María José]

I'm worn out

[hermit]

"i'm dead on my feet." is another variation on the theme.

pjt33 - the 'pumpkin' reference is from the well-known story of cinderella,
whose fancy carriage would turn back into a pumpkin after the stroke of
midnight. if a person says "oh, it's past my bedtime", someone might
jokingly respond with "so what, you're going to turn into a pumpkin?"

hermit