Isn’t it fascinating to read all the recent research on sleep, fruit flies and circadian rhythms? But it isn’t helping me to get a decent night’s kip. I try. I don’t drink caffeine after lunch, I eat early, I read a calming book in bed. But the harder I try to sleep, the less I can, because I’m worrying about what I now know will happen to me if I can’t make myself conk out: increased risk of stroke, obesity, diabetes, depression, cancer, a shorter life and, worst of all, cognitive decline. Then, if I’m still awake at 2am, sweating, brain fizzing and swirling, I switch on the wireless, which eventually sends me to sleep, but probably not the required sort of lovely deep sleep, so I wake up knackered.

This means I need a sleep in the afternoon, because my circadian rhythm is apparently dipping and I haven’t the strength to do anything else anyway, so I have a nap and then I can’t sleep at bed time. And even if I can sleep, something may wake me. I live on a corner at ground level, revellers often pass by, laughing and shouting; the dog may start dreaming and twitching, or want to go out to relieve itself; the neighbours may have a row, or a party; or the very unlikely can happen, as it did last December.

There I was, fast asleep, when this strange rustling and tinkling noise started up. What ever could it be? It was the mice, who had found the gingerbread stars on the Christmas tree, scrabbling about nibbling the stars and shaking the glass ornaments.

Who would have imagined that coming? And even if no person or animal makes the slightest movement or sound, how do I know they won’t? So I’m waiting to see if they do, which makes relaxing impossible, and I am not even a shift worker with my circadian rhythms shot to hell. What chance for them of a long, healthy life? I don’t even have to worry about getting up early in the morning. I can write this in the afternoon. Or can I? Zzz …