I've given some further thought to that study about early rising that I quoted in the previous post. Setting aside the smoking issue, I think the real take-home message is:
1) Each one of us has a chronotype, a genetically determined biological rhythm that dictates our preferred sleep and wake times;
2) Following a work schedule that doesn't match our personal chronotype may induce "social jet-lag." Symptoms might include fatigue, insomnia, cognitive deficits and mood disorders, plus possible long-term health consequences.
3) Daily sunlight exposure could help us adapt to a work schedule that doesn't match our personal chronotype, thereby offsetting the effects of social jet-lag; but
4) Most office workers don't get nearly enough sunlight to make this adjustment; and as a result
5) "More than half the population are in effect socially jet-lagged all the time, because their body clock is permanently out of synch with their working hours."
What's to be done? Healing-arts practitioners should be aware of the possible prevalence and effects of social jet-lag, and appropriately educate and treat clients who suffer from it. Enlightened employers should allow greater flexibility of work hours for employees with atypical chronotypes. Schools should pay greater attention to developmental and individual chronotype issues, and adjust school hours as necessary.
And those of us who are self-employed and self-scheduling, and "who have succeeded in making our occupation our pleasure" should be grateful that we can go to sleep when we like and wake up when we're good and ready!