The biological clock expresses circadian rhythms, whose endogenous period (tau) is close to 24 h. Daily resetting of the circadian clock to the 24 h natural photoperiod might induce marginal costs that would accumulate over time and forward affect fitness. It was proposed as the circadian resonance theory. For the first time, we aimed to evaluate these physiological and cognitive costs that would partially explain the mechanisms of the circadian resonance hypothesis. We evaluated the potential costs of imposing a 26 h photoperiodic regimen compared to the classical 24 h entrainment measuring several physiological and cognitive parameters (body temperature, energetic expenditure, oxidative stress, cognitive performances) in males of a non-human primate (Microcebus murinus), a nocturnal species whose endogenous period is about 23.5 h. We found significant higher resting body temperature and energy expenditure and lower cognitive performances when the photoperiodic cycle length was 26 h. Together these results suggest that a great deviation of external cycles from tau leads to daily greater energetic expenditure, and lower cognitive capacities. To our knowledge, this study is the first to highlight potential mechanisms of circadian resonance theory.

中文翻译：

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灵长类动物每日 26 小时光周期的生理和认知后果：探索昼夜节律共振理论的潜在机制


生物钟表达昼夜节律，其内源周期（tau）接近24小时。每天将生物钟重置为 24 小时自然光周期可能会产生边际成本，这些成本会随着时间的推移而累积，并进一步影响健康。它被提出作为昼夜节律共振理论。我们第一次旨在评估这些生理和认知成本，这将部分解释昼夜节律共振假说的机制。我们评估了在雄性非人类灵长类动物（Microcebus murinus）中实施 26 小时光周期疗法与经典 24 小时光周期疗法相比的潜在成本，测量了一些生理和认知参数（体温、能量消耗、氧化应激、认知表现） ，一种夜行性物种，其内生周期约为 23.5 小时。我们发现，当光周期长度为 26 小时时，静息体温和能量消耗明显较高，认知能力较低。总之，这些结果表明，外部周期与 tau 蛋白的巨大偏差会导致每天更大的能量消耗和更低的认知能力。据我们所知，这项研究首次强调了昼夜节律共振理论的潜在机制。