Robbie Williams soon realised he'd made a mistake when he retired from music more than a decade ago - because his brain was turning to ''Swiss cheese''.

The 'Let Me Entertain You' hitmaker decided to call it quits following the release of his flop seventh studio album 'Rudebox' in 2006, but after spending a lot of time sitting on the sofa watching bad TV he decided he had to come back and did so in 2009 with his LP 'Reality Killed The Video Star' - produced by Trevor Horn.

Speaking to The Sun newspaper, he admitted: ''Yeah, 2006 happened, I went on tour and that just fried my brains and I decided that I retired. I didn't tell anybody because I knew I'd possibly been lying to myself. I took to my home, stayed there and grew a beard, chased UFOs, watched 'The Real Housewives of Beverly Hills', Orange County, New Jersey, Atlanta, even Dallas ... And in those three years off my brain turned to Swiss cheese. A man needs a purpose, which is why I came back.''

Robbie - who has spent time in rehab on numerous occasions throughout his career for alcoholism, substance abuse, depression and even an addiction to energy drinks Lucozade and Red Bull - has previously credited meeting his wife Ayda Field in 2006 with putting him back on track.

The pop star launched his career as a member of Take That and after quitting in 1995 he joined the boys in 2010 for a new album 'Progress' and tour.

Robbie, 43, is open to rejoining the band - which now tours as a trio, Gary Barlow, Howard Donald and Mark Owen following Jason Orange's departure - in the future because he had so much fun with the guys, even though it is hard work being part of their all-action shows.

Asked if he'd return to Take That, he said: ''Yeah I would. Don't know when that would be. I'm constantly having ideas about my own stuff that I want to fulfil. It's a big commitment to re-join the band, go and promo the album for months then go on tour - it's a whole 18 months out of my life. Last time was the perfect storm in the best way. We had this critically acclaimed album, did the biggest tour the UK has ever seen and it was an amazing period in all of our lives.

''I'd like to repeat some of that. I enjoy working with them. I enjoy hiding in public. I enjoy the camaraderie and I enjoy writing songs with them too so why not?''