Dawn Lyn -- a former child star on the TV show "My Three Sons" -- is slowly recovering from the brain surgery that sent her into a coma ... she's now breathing on her own.
Tina Cole, who starred opposite Dawn back in the '60s and '70s when their sitcom was on the air, tells TMZ Dawn is continuing to improve, she's opening her eyes at times and is breathing on her own with oxygen assistance.
Tina says Dawn's husband, John, texted her a positive health update Monday night, saying Dawn was doing the best she has in the hospital since undergoing a brain operation.
Sounds like Dawn's got a big support system around her ... Tina tells us she visited Dawn in the hospital last week, holding Dawn's hand and talking to her while she was unconscious.
As we reported ... Dawn was fighting for her life last month after going under the knife to remove a brain tumor.
Rock Whitehead, who is producing an upcoming movie featuring Dawn, also posted a positive update on Dawn's heath on social media ... he says she's made major strides since arriving at the hospital over two weeks ago.