It was so obvious. I can't think why I didn't spot it earlier. For three whole years I have been unable to understand why, as soon as I sat in front of the computer, my mind turned to mush and I felt utterly exhausted. I thought the reason was psychological, but no, it's physical and there's damn all I can do about it.
Three years ago (plus a few months), Mr Grumpy had his strokes. For fear of bashing him in the night when I turned over, because he was in such pain, I moved to the downstairs bedroom, which is much noisier than the upstairs one in terms of traffic noise (though not in terms of Mr G's snoring and habit of falling asleep with the radio or TV on - I have to have silence when I sleep, he has to have noise).
Then two more things happened to make sleeping downstairs more difficult. First, some local hooligan shot the double glazing with a ball-bearing gun and broke it. Second, a new bus route started up, and it came right past my window. And there's a third, too, now I come to think of it, which is that some idiot teenagers from the estate at the end of the road have acquired those ear-splittingly noisy Italian motor scooters and roar up and down at all hours.
For the first few months, I tried earplugs, but after several trips to the doc with 'otitis externa' - eczema in the ear - I had to give them up. Then I went on line and finally found the white noise machine that exudes a gentle hiss all night and blots out a lot of the noise (though not the blasted early morning birds!)
Right. Now we're getting to the heart of it. As Mr G won't have the heating on until either of us starts turning blue, the only way I can work (it's 43 degrees F here as I write) is by having a fan heater on. Fan heaters sound like white noise. My brain thinks, 'ah, it's bedtime' and I start dozing off! So there it is. Either I turn the heater off and am too cold to work, or I turn it on and fall into a zomboid state. I can't win.
Yet another strong reason for moving, as I'll never be able to write another book till I do.