Adele felt ''very inadequate'' when she first became a mother.

The 'Someone Like You' hitmaker - who has four-year-old son Angelo with her partner Simon Konecki - has opened up about post-natal depression, admitting it ''can come in many different forms''.

She shared: ''My knowledge of postpartum - or post-natal, as we call it in England - is that you don't want to be with your child; you're worried you might hurt your child; you're worried you weren't doing a good job. But I was obsessed with my child.

''I felt very inadequate; I felt like I'd made the worst decision of my life. It can come in many different forms ...You're constantly trying to make up for stuff when you're a mom.''

And the 28-year-old singer also admitted she has a ''very dark side'' and ''can slip in and out'' of depression easily.

She added to the December issue of Vanity Fair magazine: ''I have a very dark side. I'm very available to depression. I can slip in and out of it quite easily.

''It started when my granddad died, when I was about 10, and while I never had a suicidal thought, I have been in therapy, lots.''

Meanwhile, Adele previously opened up about her smoking habit, claiming it has ''weakened'' her voice.

She said: ''The people with the best voices, they always smoke. I've given up smoking and I'm convinced that's made my voice weaker.

''Bruno [Mars] smokes like an old woman. My make-up artist will stink after having a fag. I had never noticed it before.''

Adele suffered a haemorrhage on her vocal cords in 2011, which forced her to axe her world tour so she could undergo surgery.

Speaking about the surgery, she said: ''I had laser surgery. [They] put lasers down your throat, cut off the polyp, and kind of laser your haemorrhage back together and fix it. If I decide to go on a 200-date world tour, it would happen again.''