Gorman Michael R, Kendall Magdalena, Elliott Jeffrey A
Department of Psychology, 9500 Gilman Drive, University of California, San Diego, La Jolla, CA 92093-0109, USA.
J Biol Rhythms. 2005 Feb;20(1):38-48. doi: 10.1177/0748730404271573.
Endogenously generated circadian rhythms are synchronized with the environment through phase-resetting actions of light. Starlight and dim moonlight are of insufficient intensity to reset the phase of the clock directly, but recent studies have indicated that dim nocturnal illumination may otherwise substantially alter entrainment to bright lighting regimes. In this article, the authors demonstrate that, compared to total darkness, dim illumination at night (< 0.010 lux) alters the entrainment of male Syrian hamsters to bright-light T cycles, gradually increasing in cycle length (T) from 24 h to 30 h. Only 1 of 18 hamsters exposed to complete darkness at night entrained to cycles of T > 26 h. In the presence of dim nocturnal illumination, however, a majority of hamsters entrained to Ts of 28 h or longer. The presence or absence of a running wheel had only minor effects on entrainment to lengthening light cycles. The results further establish the potent effects of scotopic illumination on circadian entrainment and suggest that naturalistic ambient lighting at night may enhance the plasticity of the circadian pacemaker.
内源性产生的昼夜节律通过光的相位重置作用与环境同步。星光和昏暗的月光强度不足以直接重置生物钟的相位，但最近的研究表明，夜间昏暗照明可能会以其他方式显著改变对明亮光照周期的同步。在本文中，作者证明，与完全黑暗相比，夜间昏暗照明（<0.010勒克斯）会改变雄性叙利亚仓鼠对明亮光照T周期的同步，周期长度（T）从24小时逐渐增加到30小时。夜间暴露于完全黑暗中的18只仓鼠中只有1只同步到T>26小时的周期。然而，在存在夜间昏暗照明的情况下，大多数仓鼠同步到28小时或更长时间的T周期。是否有跑步轮对同步到延长的光照周期只有轻微影响。这些结果进一步证实了暗视觉照明对昼夜节律同步的强大作用，并表明夜间自然环境照明可能会增强昼夜节律起搏器的可塑性。
