What has a head and a tail, but no body?

What stands like a sailor with two legs spread, has a belt and a pointed head?

I can brighten the darkest day, No light, no switch, yet chase gloom away. A smile’s my signal, a laugh my cue... What am I that lives in you?

Born of grain but never bread, I dance with bubbles, crisp but not dead. A liquid gold in frosted hold, I'm known to bring the brave more bold.

I sneak up on you with no warning, A new start, but you're still yawning. Even Garfield's under the bed, hiding from me.