Hello Tessy. Both phrases are correct. I am dead sleepy. - In this case, ''dead'' has the meaning of ''complete(ly), very''. For example, ''The exam is dead easy. I am dead hungry.'' I am sleepy to death. - In this case, ''to death'' refers to ''extremely''. When somebody is bored, frightened, sleepy, etc. to death it means that somebody is extremely bored, frightened, sleepy, etc. I hope this is helpful :)

Hi Tessy: Neither of these is correct: (I am dead sleepy; I am sleepy to death). "I am dead tired" is exactly right. Of course it means that a person is extremely tired.

I'm not a native speaker, but I always first check and then give an answer. According to dictionaries, both phrases are correct, as I have already said. Maybe some of them are not frequently used (we can often hear ''I'm dead tired.''), but both phrases ARE correct. Here's the link: http://dictionary.cambridge.org/dictionary/english/dead

'I am dead sleepy' or 'I am dead tired' - both correct I have never heard anyone say 'I am sleepy to death'. In the UK, we do have an expression, 'I am bored to death', which of course means something different.