Rial Ruben Victor, Nicolau María Cristina, Gamundí Antoni, Akaârir Mourad, Aparicio Sara, Garau Celia, Tejada Silvia, Roca Catalina, Gené Lluis, Moranta David, Esteban Susana
Laboratori de Fisiologia, Institut Universitari de Ciències de la Salut, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain.
Sleep Med Rev. 2007 Aug;11(4):311-25. doi: 10.1016/j.smrv.2007.03.001. Epub 2007 May 4.
Rest in poikilothermic animals is an adaptation of the organism to adjust to the geophysical cycles, a doubtless valuable function for all animals. In this review, we argue that the function of sleep could be trivial for mammals and birds because sleep does not provide additional advantages over simple rest. This conclusion can be reached by using the null hypothesis and parsimony arguments. First, we develop some theoretical and empirical considerations supporting the absence of specific effects after sleep deprivation. Then, we question the adaptive value of sleep traits by using non-coding DNA as a metaphor that shows that the complexity in the design is not a definitive proof of adaptation. We then propose that few, if any, phenotypic selectable traits do exist in sleep. Instead, the selection of efficient waking has been the major determinant of the most significant aspects in sleep structure. In addition, we suggest that the regulation of sleep is only a mechanism to enforce rest, a state that was challenged after the development of homeothermy. As a general conclusion, there is no direct answer to the problem of why we sleep; only an explanation of why such a complex set of mechanisms is used to perform what seems to be a simple function. This explanation should be reached by following the evolution of wakefulness rather than that of sleep. Sleep could have additional functions secondarily added to the trivial one, although, in this case, the necessity and sufficiency of these sleep functions should be demonstrated.
变温动物的休息是生物体适应地球物理周期的一种表现，这对所有动物来说无疑是一项有价值的功能。在本综述中，我们认为睡眠对于哺乳动物和鸟类的功能可能并不重要，因为睡眠相较于简单的休息并没有提供额外的优势。这一结论可以通过使用零假设和简约论证得出。首先，我们提出一些理论和实证依据来支持睡眠剥夺后不存在特定效应的观点。然后，我们以非编码DNA为隐喻来质疑睡眠特征的适应性价值，这表明设计上的复杂性并非适应性的确凿证据。接着，我们提出睡眠中几乎不存在（如果有的话）可选择的表型特征。相反，高效清醒状态的选择才是睡眠结构中最重要方面的主要决定因素。此外，我们认为睡眠调节只是一种强制休息的机制，在恒温动物出现后，休息状态受到了挑战。总的来说，对于我们为什么睡眠这个问题没有直接答案；只有对为什么要用如此复杂的一套机制来执行看似简单的功能的解释。这个解释应该通过追溯清醒状态的进化而非睡眠的进化来达成。睡眠可能次要地附加了一些额外功能，不过在这种情况下，这些睡眠功能的必要性和充分性应该得到证明。
