The impact of daytime light exposure on diurnal and circadian rhythms in the diurnal rodent Rhabdomys pumillio

白天光照对日间啮齿动物横纹鼠昼夜节律的影响

• 批准号: BB/P009182/1
• 负责人: Robert Lucas
• 金额: $ 64.25万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FP009182%2F1
• 关键词: impact; daytime; light; exposure; diurnal

Throughout our evolutionary history, the rotation of the earth upon its axis imposed a highly predictable and large amplitude twenty four hour rhythm in the amount of light to which we were exposed. The advent of artificial lighting has fundamentally disrupted this relationship in two ways. Firstly, it allows us to experience unnaturally high levels of light at night. Secondly, it allows us to spend most of our waking time indoors, exposed to unnaturally low light levels during the day. Significant attention has been paid to the deleterious effects of light at night, with evidence from both animal and human studies that this disrupts the endogenous timing mechanisms (circadian clocks) that define 24hr rhythms in our physiology and behaviour and inhibits sleep, with knock-on consequences for general health and daytime performance. By contrast, the impact of reduced light intensity during the day has been much less studied. This is a shame because, while it is practically inconceivable that we could reverse the progress of the last >100 years and persuade people to avoid unnatural sources of light at night, increasing levels of daytime light could be readily achieved by changes to architectural lighting design or even just by encouraging people to spend more time outdoors. There is evidence from humans that increasing light during the day improves alertness and cognitive performance, and that in the long term it can change the phase, increase the amplitude, and reduce the photosensitivity of circadian rhythms. However, the literature is sparse and lacks a systematic study of the impact of daytime light levels on temporal physiology. Here we set out to address this deficit and ask what impact, if any, changing daytime light exposure has on 24hr rhythms in behaviour and physiology. We then continue to ask whether increases in daytime light intensity can ameliorate some of the disruptive effects of light at night. We will address these questions by studying laboratory rodents. There is a rich history of translating findings from laboratory animals to humans in the field of circadian biology. Working in laboratory animals has the huge advantage of allowing researchers to carefully control environmental conditions over many days/weeks in a way that is difficult to achieve in human studies in the laboratory, let alone under field conditions. Fortunately, general principles established in the laboratory have proven to have good utility for understanding rhythmic physiology of humans in the real world. A substantial challenge in applying this well-worn approach to the questions posed in this proposal is that commonly employed laboratory rodents (mice, rats, hamsters) are nocturnal and would not normally experience bright daytime light. Indeed, in the lab they employ behavioural strategies to reduce their daytime light exposure - build nests, seek shade, shield their eyes during sleep. If we are to understand the impact of changing daytime light levels on circadian organisation and the disruptive effects of light at night we therefore need a species that, like humans, actively seeks daytime light exposure. We have established a colony of such animals in Manchester in preparation for this proposal. Rhabdomys pumillio is a species of mouse from Africa, slightly larger than ordinary lab mice. Importantly though, in both their natural environment and in the lab they are substantially day active. Accordingly, they also have a visual system that, like our own, is optimised for seeing in bright light. In this proposal we will carefully change the intensity of daytime light and monitor the impact on daily rhythms in behaviour and physiology in Rhabdomys. We will then ask whether increasing daytime light exposure ameliorates the disruptive effects of nighttime light exposure, with especial emphasis on the sort of nocturnal lighting patterns experienced by people.

在我们的进化史中，地球绕其轴的旋转在我们所接触的光量中施加了高度可预测和大幅度的24小时节律。人工照明的出现从两个方面从根本上破坏了这种关系。首先，它让我们在夜间体验到不自然的高亮度。其次，它使我们能够将大部分清醒时间花在室内，暴露在白天不自然的低光照水平下。人们对夜间光线的有害影响给予了极大的关注，动物和人类研究的证据表明，这会破坏定义我们生理和行为中24小时节律的内源性计时机制（生物钟），并抑制睡眠，对一般健康和白天表现产生连锁反应。相比之下，白天光照强度降低的影响研究得更少。这是一个耻辱，因为虽然我们几乎无法想象我们可以扭转过去100年的进步，并说服人们避免在夜间使用非自然光源，但通过改变建筑照明设计，甚至只是鼓励人们花更多的时间在户外，可以很容易地实现增加白天光线的水平。有来自人类的证据表明，白天增加光照可以提高警觉性和认知能力，从长远来看，它可以改变相位，增加振幅，降低昼夜节律的光敏性。然而，文献是稀疏的，缺乏系统的研究白天的光照水平对时间生理的影响。在这里，我们着手解决这一缺陷，并询问改变白天光照对行为和生理的24小时节律有什么影响。然后，我们继续询问白天光线强度的增加是否可以改善夜间光线的一些破坏性影响。我们将通过研究实验室啮齿动物来解决这些问题。在昼夜节律生物学领域，将实验室动物的发现转化为人类的研究成果有着悠久的历史。在实验室动物中工作的巨大优势是允许研究人员在许多天/周内仔细控制环境条件，这在实验室的人类研究中很难实现，更不用说在野外条件下了。幸运的是，在实验室中建立的一般原则已被证明对理解真实的世界中人类的节律生理学具有很好的效用。将这种常用方法应用于本提案中提出的问题的一个重大挑战是，常用的实验室啮齿动物（小鼠、大鼠、仓鼠）是夜行动物，通常不会经历明亮的白天光线。事实上，在实验室里，它们采用行为策略来减少白天的光线暴露-筑巢，寻找阴凉处，在睡眠时保护眼睛。如果我们要了解白天光照水平变化对昼夜节律组织的影响以及夜间光照的破坏性影响，我们需要一个像人类一样积极寻求白天光照的物种。我们已经在曼彻斯特建立了一个这样的动物群，为这项提议做准备。Rhabdomys pumillio是一种来自非洲的小鼠，比普通的实验室小鼠稍大。但重要的是，在自然环境和实验室中，它们基本上都是白天活跃的。因此，它们也有一个视觉系统，就像我们自己的一样，是为了在明亮的光线下看到而优化的。在这项提案中，我们将仔细改变白天光线的强度，并监测对横纹鼠行为和生理的日常节律的影响。然后，我们会问，增加白天的光照是否会改善夜间光照的破坏性影响，特别强调人们所经历的夜间照明模式。

项目成果

Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults.

• DOI: 10.1371/journal.pbio.3001571
• 发表时间: 2022-03
• 期刊: PLoS biology
• 影响因子: 9.8
• 作者: Brown TM;Brainard GC;Cajochen C;Czeisler CA;Hanifin JP;Lockley SW;Lucas RJ;Münch M;O'Hagan JB;Peirson SN;Price LLA;Roenneberg T;Schlangen LJM;Skene DJ;Spitschan M;Vetter C;Zee PC;Wright KP Jr
• 通讯作者: Wright KP Jr

The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN).

• DOI: 10.1038/s41598-017-11184-2
• 发表时间: 2017-09-05
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Dobb R;Martial F;Elijah D;Storchi R;Brown TM;Lucas RJ
• 通讯作者: Lucas RJ

Daily electrical activity in the master circadian clock of a diurnal mammal

• DOI: 10.1101/2020.12.23.424225
• 发表时间: 2020-12
• 期刊: eLife
• 影响因子: 7.7
• 作者: Beatriz Baño-Otálora;Matthew Moye;T. Brown;R. Lucas;C. Diekman;M. D. Belle

Melanopsin Contributions to the Representation of Images in the Early Visual System.

• DOI: 10.1016/j.cub.2017.04.046
• 发表时间: 2017-06-05
• 期刊: Current biology : CB
• 作者: Allen AE;Storchi R;Martial FP;Bedford RA;Lucas RJ
• 通讯作者: Lucas RJ

Exploiting metamerism to regulate the impact of a visual display on alertness and melatonin suppression independent of visual appearance.

• DOI: 10.1093/sleep/zsy100
• 发表时间: 2018-08-01
• 期刊: Sleep
• 影响因子: 5.6
• 作者: Allen AE;Hazelhoff EM;Martial FP;Cajochen C;Lucas RJ
• 通讯作者: Lucas RJ