The troubled star - who spent just 23 days of a court-ordered 90-day rehab stint at the UCLA Medical Center last month - voluntarily began a substance abuse programme at a facility in Southern California on Monday night (27.09.10), and reportedly plans to stay there until her next court hearing on October 22.
After failing two drugs tests last week, the `Machete` actress returned to prison on Friday (24.09.10), but ended up spending just a matter of hours behind bars after posting $300,000 bail.
However, the 24-year-old star - who spent just 13 days of a 90-day jail term behind bars in July - could be faced with prison after her next court appearance for violating the terms of her probation for a 2007 driving under the influence (DUI) conviction.
According to gossip website RadarOnline.com, Lindsay spent her final few hours of freedom before returning to rehab reading self-help book `The Power of Rest` by Dr. Matthew Edlund.
An insider revealed: "Lindsay hopes to use this book to help restructure her sleeping patterns so she can function better. She has been shooting films into the wee hours of the morning since she was 11 or 12 years old and then sleeping in trailers while on the set. She never established a normal sleeping pattern.
"She was recommended the book by both a doctor and a friend and hopes it will guide her in the right direction."