[katieHaylor (OP)]

Tuomo sent in this question:

I do shift work and really enjoy variable working times. If I have to wake up very early next morning - say 3AM - something happens in my body on the previous day that makes me extremely tired at 6PM and I have to go to sleep. This is great of course because then I get the 7-9hrs of sleep that's required.

However, if I don't need to be anywhere the next day I can stay up til 10PM to midnight just like any other person. The level of tiredness in the evening seems to be independent from my rhythm.

It seems that my brain has some sort of conscious ability to extract melatonin into my bloodstream when I need to wake up early next morning. I'm curious since I've understood melatonin is something you cannot extract consciously? Other than by taking a pill.

Is this normal, or am I a one-off freak of nature who seems to evolved for shift work?

What do you think?

[alancalverd]

I think the clue lies in the throwaway phrase "really enjoy". Anticipation of a challenging and satisfying day at work, provided it doesn't carry stress (there's a difference between working hard for a reward and banging your head against a boring or impossible task for no reward) can trigger adrenalin followed by noradrenalin and a quick transfer to sleep.

We generally have pre-sleep rituals that turn on the melatonin. It may be the hot bath/whisky/cocoa as much as the anticipation of the morrow that flips Tuomo into sleep. It (ritual, not whisky) is supposed to work for babies. My own favorite is the cabin crew safety demonstration: any time of day or night, any ship or plane, anywhere in the world, as soon as they point to the exit doors, I'm in the land of Nod.

There is also the possibility of synchronising an early bedtime with a "natural low". I find that a few minutes' REM sleep whenever nature ordains it (about every 2 hours) can keep me functioning effectively for 36 hours or more. If there is no alarm call, this can slide into "proper" sleep, but simply going to bed when not tired and ready, doesn't.