In the night,There's no light..

Hey there.I've been playing minecraft since 1.7.2
The problem (bug) is,if its night time..There's only light...no darkness??
if theres an torch placed or glowstone,doesnt make sense,theres no darkness.n it looks ugly.n in caves there is darkness.FIX PLZ

I've a Mac OS X Version: 10.5.8 PowerPC