Demi Lovato feels ''lonely''.

The 'Cool for the Summer' hitmaker is currently single and she admits that whilst being out of a relationship has allowed her to ''just have fun'', it also makes her feel alone from time to time too.

She said: ''I'm single, and I'm 25 years old, and I'm living by myself, and so I wanted to write about it. Some of the perks include not taking life, or anything, too seriously, and just having fun. And then sometimes it gets lonely.''

And the 25-year-old singer - who previously dated actor Wilmer Valderrama on and off for six years - insists none of her songs are ''made up'' but she does ''disguise'' them a little bit if it is too obvious who they are about.

She added: ''I don't think that any of my songs are necessarily 'made up'. I relate to all of them through personal experiences. There are times when there are people that I write about and I don't want it to sound too obvious, so I'll disguise it a little bit. And for the most part, my fans know what's up.''

Demi - who previously battled with an eating disorder and alcohol and drug abuse - bared her soul for her documentary 'Demi Lovato: Simply Complicated' and felt comfortable opening up about it because she knows it will help someone somewhere.

She told USA Today: ''Some of the ways that I got comfortable with the cameras is knowing in those moments when I'm being vulnerable, or when I'm opening up, I know that it's going to help someone who may be going through the same thing I am. So just keeping that in mind, in the back of my head, when you're filming is important.''