The 56-year-old, best known for her long-running role in Coronation Street, hit a low point in 2008 after the business she ran with her husband went bust and she ended up steeped in debt.
Callard's family eventually staged an intervention and had her admitted to rehab clinic The Priory to deal with her issues.
Speaking during an interview on Piers Morgan's Life Stories, she said: "I tried maybe half a dozen times (to end my life), but it wasn't a cry for help at all.
"I'd known for quite a while that I wasn't myself, but I didn't really know what to do about it... Apparently I took the light bulbs from the light fittings and tried to slash my wrists with them. I stored up tablets... I have to say I can't remember. I just wanted my life to stop...
"I was going to work and I was still filming and I didn't really talk to anyone about it and on that day they took me into The Priory in the early hours of the next morning and (my husband) John said, and my doctor said, I looked like a 100-year-old woman. They tried different medications but none of them seemed to work."
Callard admits she subsequently struggled with work after returning to the TV show as the treatment she received affected her memory: "I actually, now, don't know how I learnt my lines. It was really a double life at that point... I couldn't sign my autograph because I couldn't remember how to spell my name. I truly couldn't write my name for the first six months."
The actress has now recovered, but insists she will remain on medication for "at least another couple of years".