Lindsay Lohan's London party roadshow has provoked further fears for her mental and physical well-being.

The Mean Girls star appears to have spent most of her time club hopping in the wake of on/off girlfriend Samantha Ronson – who is in London for a series of DJ gigs – since arriving in the UK capital from Paris on Tuesday evening.

Lindsay's persistence appeared to pay off on Sunday when she was snapped looking very pleased with herself as she emerged from Sam's South Kensington hotel at 5pm on Sunday.

Lindsay and Sam are all smiles as they leave the DJ's London hotel separately on Sunday afternoon

The pair had spent the night together there after partying at Bungalow 8 until 4.30am.

Lindsay emerges from Bungalow 8 at 4.30am on Sunday morning

Meanwhile, an observer has described Lindsay's behaviour at the Cuckoo club on a previous night as like watching someone in the middle of a “complete breakdown.”

“She just wouldn’t stop saying she felt caged,” a source tells Britain’s Daily Mirror

“She was just not all there and it really was like watching a broken girl in the middle of a complete breakdown.

“Everyone with her was actually very concerned about her. She seemed like a girl on the brink of self-destruction.

“Lindsay - who had a vodka in hand throughout the night - squirmed around as if trying to hide in a ball on the floor.”

Lindsay has hit back at US reality TV doctor Dr. Drew (of Celebrity Rehab fame), who spoke publicly about his fears for the actress last week.

She posted on Twitter: “I thought REAL doctors talk to patients in offices behind closed doors,” she Tweeted on Friday, not referring directly to Dr. Drew. “Am I wrong? Hmmmmm. I think NOT! Yay!”

It's a valid point - but doesn't mean Dr Drew isn't right!