This could explain her apparent mood swings on the set of Cheers. And she did attempt suicide back in 2004, which would lend credence to the notion that she has serious emotional baggage/issues. Plus, a lot of undiagnosed (and diagnosed) bipolar people abuse prescription drugs. They are basically self medicating.
http://www.suicide.org/shelley-long-attempts-suicide.html
https://www.datalounge.com/thread/12398176-shelley-long
I think there is too much bipolar-diagnosis being cited in general. In other words, bipolar mood-swings are more protracted. And going from mania to the point of delusion, then debilitating depression without any discernible reason nor incident. She could just be moody, or "suffering" from a lost career.
shareI wouldn't like to speculate. Shocked to hear about that suicide attempt though, I had no idea about that.
I always enjoyed her work on Cheers and I wish her the best.
Everybody has Bi-Polar
Sound a whole lot better than Manic/Depression which is what it used to be called
That's the Psycho-Therapeutic Industry hard at work normalizing their failures