Why Should We Rise with the Lark?

Abstract

In 1826 the essayist Charles Lamb criticized the British precept that “we should rise with the lark” as a popular fallacy. His advice was: “For a mere human gentleman we take ten to be the very earliest hour at which he can begin to think of abandoning his pillow” [21]. This is in strong contrast to the note which James Boswell, while travelling in Holland, made in his diary on September 25, 1763: “At present, I rise every day early, a practice which contributes much to the preservation of health because it knits up the nerves and gives hardiness and vigour to the constitution” [23]. To complicate matters, the time of going to bed could be discussed; there comes to mind the provocative assertion of Elias Canetti [15]: “A respectable man retires at nine.” We may ask, however, why we have to wake up at all. And how is it that the lark gets up so early? At the time of Charles Lamb the answer would have been: the lark wakes up when, during dawn, the intensity of illumination reaches a certain, species-specific threshold — it is the alternation of light and dark which determines the rhythm of wakefulness and sleep. In the meantime we have learned that the lark does not need external signals for rising and roosting but relies upon an internal biological clock. Here, I briefly present data that indicate the existence of such a clock in animals and then discuss in more detail aspects of temporal organization in man.