The adaptability of the human body also never fails to amaze me. My wife is seriously into her sleep. Most nights she'll have dozed off on the sofa by 9.30 until I throw cushions at her for snoring, then would be up to bed and straight back to sleep in an instant until 7am.
We've just had our first child who's now 8 weeks old, so her old pattern is a distant memory. For the first 2 to 3 weeks she was wrecked in a morning however by weeks 4 to 5 her body had adapted to the reduction in sleep and she's now operating at least around 95% on what some nights can be half the sleep she used to have.
Indeed. We are creatures of habit, and our bodies get used to our routines.
When I was unemployed for a few months, I got into the habit of going to bed in the early hours and waking up late. It was the middle of the winter, and I sometimes went days at a time without seeing daylight. When I got a job, I still went to bed very late, but now I had to get up in the mornings. Having survived an initial groggy fortnight or so, I was functioning just as well and was just as wide awake on a regular 6 hours sleep a night as I'd been only a month before on 10-11 hours.
(In a vaguely analogous sense, I discovered when I was travelling that I used to get hungry at mealtimes, but if I didn't have and couldn't get any food, I could just ride it out, and after an hour or so, when it was no longer 'lunchtime', my body would sort of shrug its shoulders, accept that that was that, and give up. The feeling of being hungry would simply fade away, and I wouldn't start to get hungry again until dinner time.)
