Why does it get dark so fast in minecraft?

I downloaded the Demo version of Minecraft, it seems to get dark not even 5 minutes after the sun comes up, it doesn't even give the creepers enough time to burn up.
It just seems impossible to get anything done because I cant make a weapon unless I can walk around and find materials, and that's really hard when I die every 2 minutes.

of anyone could help me I would really appreciate it.

Read more: Why does it get dark so fast in minecraft?