Are they talking about drugs or love? Part 2 of 100 (lyrics included in descriptbox)

Ain't no sunshine when she's gone

It's not warm when she's away

Ain't no sunshine when she's gone

And she's always gone too long

Anytime she's goes away

Wonder this time where she's gone

Wonder if she's gone to stay

Ain't no sunshine when she's gone

And this house just ain't no home

Anytime she goes away

And I know, I know, I know, I know

I know, I know, I know, I know, I know

I know, I know, I know, I know, I know

I know, I know, I know, I know, I know

I know, I know, I know, I know, I know

I know, I know

Hey, I ought to leave young thing alone

But ain't no sunshine when she's gone, whoa-whoa

Ain't no sunshine when she's gone

Only darkness every day

Ain't no sunshine when she's gone

And this house just ain't no home

Anytime she goes away

Anytime she goes away

Anytime she goes away

Anytime she goes away

(Source musicmatch)

Fun fact: dude forgot the words and repeated i know in the recording session to get through the song and finish it later but they kept the i know part because it sounded good.