Friday: For some strange reason, I have been sent two copies of a new Health Encyclopaedia by a certain Dr Robert Youngson. According to the back cover, Dr Thomas Stuttaford of the Times thinks it "should prove invaluable in the home" - a compliment with the scrawled, automatic ring of " 'A tour de force,' Anthony Burgess" on the back of a novel, but even so it would be rude not to dip in for five minutes and get a flavour of Dr Youngson's work.
Saturday: I awake tetchy and prickly-eyed, having passed a brief night (I didn't drop off until after 4am) to find my wife sitting on the edge of the bed in a menacingly straight-backed manner. She is holding my encyclopaedia. "What is this?" she asks, pointing at the annotation on page 292. "That? A note on a disease called fatal familial insomnia," I tell her, glancing down, "a terminal, genetically determined disease . . ." I look up to find myself alone.
Sunday: Last night I hardly slept again, and now a familiar jittery sensation ripples along the area beneath my ribs. It's panic, of course, and so intense is the need to gainsay the terror by articulating it that I wait until Rebecca is a captive audience in her bath before striking. "This fatal familial insomnia . . ." I tell her, and she slides irritably beneath the water. When she surfaces, I go on. ". . . occurs between 40 and 60, and I think it killed my grandmother Suds."
"She claimed not to have slept for more than 20 minutes since 1936." From the thinning of her lips, Rebecca is preparing one of her Socratic dialogues.
"How long does it take to kill?" she asks.
"It is fatal," (I have memorised the entry) "within seven to 33 months of its onset."
"And when did Suds die?"
"In 1990, a week before the FA Cup final," I reply.
"At what age?"
"So she was 24 years too old and suffered it for 50-odd years too long. And you really think this illness killed her?"
"Well," I reply, "she might have had a new variant strain."
When a family-size bar of Imperial Leather clips me on the left temple, I leave Rebecca to her bath.
Sunday: The river of marital tension, which has been rising for 24 hours, bursts its banks when Rebecca angrily accuses me of ruining Celebrity Big Brother by muttering ceaselessly throughout. The truth is, I'm worried about Vanessa. "She's becoming paranoid," I explain. "It says here on page 557 that factors include lowered self-esteem, distrust and suspicion of others, and social isolation. That's Vanessa all over." I am shouting now because the volume has been turned up to maximum, and when the neighbours begin banging on the wall I take the book and a bottle of Glenlivet and retire morosely to bed.
Monday: Say what you will, this encyclopaedia is wide-ranging. There is even an entry on frottage, the practice of "rubbing the body against another person for the purposes of sexual gratification . . . without exposing himself the active male rubs his genitals against a woman's buttock or thigh."
Fascinating, but what's it doing here?
Tuesday: I awake jumpy and neuralgic after passing a troubled night, in which, during the one very brief period of sleep, I dreamed of Andrew Neil. We are fellow housemates in a journalists' Big Brother (it's for charity: we're raising money for the Barclay brothers' internet division) when I spontaneously develop fatal familial insomnia. Andrew picks up a guitar and tries to soothe me to sleep by singing Simon and Garfunkel songs. "When you're weary," he croons, "when you're a poisonous little prick/ When tears are in your eyes . . ." But it's hopeless, and when I begin to scream, Dr Thomas Stuttaford leaps naked from the hot tub, where he has been sporting with Janet Street-Porter and Libby Purves. When he charges in, with syringe drawn to sedate me, I awake.
Wednesday: The illness appears to have gone into remission, and I awake after 11 hours' sleep refreshed but annoyed to find the encyclopaedia still missing. I first noticed its absence late last night, and this morning a copious search of this Bermuda Triangle of a house (the book joins 23 other medical textbooks, 11 thermometers, three stethoscopes, an enema kit, two blood-pressure-testing devices and a range of Chinese herbs to have vanished in four years) reveals nothing. Still, how prescient of Bloomsbury to have sent two copies. For now I think the other is best left in the office.