I know someone who used to get manic autumn and spring. The increasing light could explain it in spring, but not the decreasing light in the autumn. So what gives? Maybe part of it was allergies? I have read that immune reactions and inflammation can trigger problems. Maybe??

Most of what I read connects allergies and asthma with depression, but you know how we tend to cycle, so what goes down must come up. Here is an article from the New York times about the allergies and depression: Allergies can Increase Risk of Depression
but here is something with links about inflammation preceding bipolar.

Jaspar