Is it normal for suicidal thoughts to calm me down?

I've been struggling with severe depression for the past 6 years or so. I never really had suicidal thoughts until about 2 years ago. It has been like a roller coaster the past year, where the peaks of happiness only lead into a deeper decent into sadness.

The only thing I've noticed that helps me climb up out of depression is when I'm at rock-bottom and those nonchalant suicidal thoughts begin to populate my mind. It makes me view life from a different perspective I suppose. Typically the thoughts last several days but I am now accustomed to them just going away as I climb back up that rollercoaster ride.

So now in my brain I have this association with these suicidal thoughts where they are a necessary part of the process in order for me to be happy. My fear is that one day, while at the bottom, the ride never begins the trip back up. I don't think I am mentally strong enough anymore to withstand an unexpected drop while at what I think is the bottom.

Sorry for the rant.