Bipolar Disorder is characterised by swings between elevated mood (mania) and depression. On the healthier end of mania, the individual can be energetic and highly productive, but in an unhealthy state it can include erratic and impulsive behaviour, poor decision making and insomnia. As its most severe level it can include psychosis (distorted beliefs about the world).

What goes up usually comes down, and when Bipolar sufferers come down they usually come all the way down into depressive states. We’ll include some separate posts exploring depression in the future, but for this post I’ll just give Wikipedia’s description of it:

feelings of sadness, anxiety, guilt, anger, isolation, or hopelessness; disturbances in sleep and appetite; fatigue and loss of interest in usually enjoyable activities; problems concentrating; loneliness, self-loathing, apathy or indifference; depersonalisation; loss of interest in sexual activity; shyness or social anxiety; irritability, chronic pain (with or without a known cause); lack of motivation; and morbid suicidal thoughts

How does the elevated mood (mania) of Bipolar Disorder affect BDSM play? A poster on FetLife described it this way:

When those with bipolar are in active manic states we tend to do everything fast, think, act, decide, perceive. As long as we feel protected by who we play with, I find that play has a lot of positive benefits. Everything seems bigger, brighter, better and this can make for any play to be positive, rewarding, and pleasant. Someone who is manic is much easier to read than someone who is not. We have little or no filter, and this should make the Top’s job easier. I personally find play very relaxing. It helps to calm me down a bit even if only for a short while. I’m less inhibited which is always a good thing during play. I am so in tuned with my physical body and mental feelings that my husband does not have a lot of detective work to do before, during or after play. We search for subspace, only because this aids in relaxation of not only my body, but also of my mind and I can stay there a while even after play, knowing my husband has me safe and comfortable in his arms. Needless to say, I love play, especially when manic.

She goes on to ask an important question.
Should BDSM and play be encouraged or discouraged in these circumstances, and in cases of mental illness in general? And if so, how should it be negotiated?

I don’t have answers, but I’d encourage you to follow the link and read the responses. There’s a lot of wisdom in them.