It's been about a week since Lindsay Lohan entered rehab at the Wonderland Center addiction-treatment facility ... she's been lying low.
But according to one of her friends, it seems she's happy & enjoying it! Her friend says: "She's been sending text messages from rehab saying she's the happiest she has ever been. She seems under control right now."
Well, I guess if she's not happy at Wonderland, then she must be crazy! Because this center is better than the outside world!

There's a spa, yoga instructors & beauty consultants. Lohan has been exercising, taking hikes & attending treatment meetings.
What's even cooler, is that she can step out for a break ... She was spotted eating out with her friends a couple of days ago!
Ha! She must be enjoying it!