I agree with Ben: it means he was very tired. The "not" reverses "a little"... therefore, "very". You'll see this negated form used in order to convey the meaning indirectly. "That was a stupid thing to say." (direct) - "That wasn't a very intelligent thing to say." (indirect)

It means "He is very tired." "Not a little" means "very; very much; a great deal of". It is standard usage and perfectly correct grammar.

Hi Ruby, Its actually not good grammar..and really depends on the context. But it would usually be a way of emphasizing that he WAS tired!

We need more information. It sounds like the person "was not even a little tired" meaning they were wide awake It is possible that they could say "He was not a little tired, but very tired!" However they would probably make it more obvious if that were the case. (I'm guessing it means they were wide awake) Hope this helped!

Here is the link to the relevant entry in the Oxford Dictionary, which may be of interest to some members here: http://www.oxforddictionaries.com/definition/english/not-a-little?q=not+a+little On that page there is also a link to the American dictionary, which gives the same explanation.