Wimpy neurologists talk about "exacerbations" when talking about MS and heat. That clinical term, like nearly all clinical terms, stays clear of the nuts and bolts of the actual issue, which sucks almost unremittingly.
Not until the wee hours of the night do I feel like a functional, halfway normal human being. Before that, it seems that I writhe in my bed and silently endure an almost endless lethargy. This, I have to say for the millionth time, has NOTHING to do with simple depression. Rather, it is a pathological response to heat, humidity, and whatever else the sun diabolically brings with it.
A normal person gets up, a bit groggily, and by the afternoon finds that his energy level has dropped 25% or so. Someone with MS already starts the day with half a tank that never gets replenished, so by afternoon I, for example, am completely bone-dry when it comes to energy. I have nearly nothing more to give, and so I wait for the sweet embrace of death. Er, sleep. (Just kidding--I've said many times that suicide always seems like such a cowardly act. Rub some dirt on it, as a high school football coach might say, suck it up, and get up.)
Everyone loves summer. Not me. I feel especially proud of the fact that, even before MS was even in my lexicon, I much preferred autumn. Summer drags on, with only heightening discomfort, until fall blows on your simmering loins.
That sounds strangely sexual, but think of it in culinary terms. If that's still sexual to you, I suggest you consult a psychiatrist.
Rick