Lindsay Lohan's friends are concerned about her recovery.

The 'Machete' actress - who completed a 23-day stint in rehab earlier on Tuesday (24.08.10) - is said to be worrying friends as she has looked to be on the straight and narrow previously before heading back to her hard-partying ways.

A source explained: "Lindsay says she's determined to stay sober and focus on work.

"But it's too soon to tell what will happen. We've seen these moments of 'purity' before, but as soon as she gets a taste of the nightlife and the drama, she usually falls back into old habits fast."

A friend of the 24-year-old star's reveals she is concerned as she doesn't like to be bored.

The pal told People magazine: "She doesn't like staying put and she doesn't like being bored. She needs to be constantly stimulated; it's not uncommon for her to be up texting from 4am to 8am. The people in her life are on a constant roller coaster."