Lohan, 25, wasn't taken to a hospital and emergency workers called to her room left after determining she was OK.
"She was on set last night at 7 p.m. and worked through the night until 8 a.m. this morning," Lohan's publicist Steve Honig told People.com.
"She took a nap before shooting her final scene. Producers were concerned when she did not come out of her room and called paramedics as a precaution," Honig said.
"Lindsay was examined and is fine, but did suffer some exhaustion and dehydration. ... She is resting now and is hoping to be back on set later this afternoon."
Lohan has a history of drug and alcohol addiction but has said in recent months she is committed to her sobriety.