Interesting. Much matches my own experience and some seems quite at odds with it. Whether that is down to unresolved scientific study or my particular quirks, rhythmic or otherwise, I don't know.

I have been an early riser for most of my life and very much enjoy sunrise times. I'm also much more comfortable in the dark and spent several years working only at night.

I've also been one to outlast most others at parties and yet be up to clean the mess and make breakfast whilst others continued to sleep.

Now, at almost 80, I find that I have to fight with myself to go to bed at a 'reasonable' time in order to get enough sleep and still be able to walk with my dog in the dark and meet the dawn. If I stay up late, as I used to do, as you say is common for you, often until 3 or 4am, I find that I just have to take naps during the day and rarely feel rested.

So, I wonder, are our circadian rhythms more nurture than nature, response to the societies in which we live and how they organise our lives through school and working hours, services and such?

Thanks, anyway, for the read - it certainly jogged me into contemplating my own experience and the similarities and differences with yours.