thought I would put a new post to your question as others might not see it as it your enquiry was under a different posting. As a sad sufferer I am very low in winter and in spring I make a concious effort to control my exhuberance and 'mania' so it's not impossible to be incorrectly diagnosed. It is also not impossible that he could have a dual diagnosis of both conditions either. I would say that a general rule he is unlikely to be high during Jan and Feb as most people are at their lowest (unless we get freak weather!).
There is more information available from S.A.D.A the seasonal affective disorder association and there are also books that you could look at 'Winter blues' by Norman Rosenthal and Seasonal affective disorder by Angela smyth. I would advise keeping a diary of behaviour, mood and weather e.t.c to see if it looks seasonal. I can judge the months by my patterns of behaviour :)
Have you discussed this with the psychiatrist or G.P? Hope this is useful and keep a firm grip on the credit cards! :wink: