You sleep alone, and it's just too bad for the energy!

When she had been sleeping alone for far too long.

It would have hurt him if she had left his bed to sleep alone.

He wasn't going to start sleeping alone at his age.

"Perhaps it would have been better for us all if you hadn't slept alone last night."

I wonder if I'll ever get used to sleeping alone?

The bed she slept alone in was small but wide enough for two.

And before you know it, you're sleeping alone for a while.

He'd held to his word, sleeping alone, for almost three months.

"She is now the only one of us sleeping alone."