Aside from the homeostatic and circadian components, light has itself an important, direct as well as indirect role in sleep regulation. Light exerts indirect sleep effect by modulating the circadian rhythms. Exposure to short light-dark cycle (LD 1:1, 1:1 h light - dark) eliminates the circadian sleep regulatory component but direct sleep effect of light could prevail. The aim of the present study was to examine the interaction between the light and the homeostatic influences regarding sleep regulation in a rat model. Spontaneous sleep–wake and homeostatic sleep regulation by sleep deprivation (SD) and analysis of slow waves (SW) were examined in Wistar rats exposed to LD1:1 condition using LD12:12 regime as control. Slow wave sleep (SWS) and REM sleep were both enhanced, while wakefulness (W) was attenuated in LD1:1. SWS recovery after 6-h total SD was more intense in LD1:1 compared to LD12:12 and SWS compensation was augmented in the bright hours. Delta power increment during recovery was caused by the increase of SW number in both cases. More SW was seen during baseline in the second half of the day in LD1:1 and after SD compared to the LD12:12. Increase of SW number was greater in the bright hours compared to the dark ones after SD in LD1:1. Lights ON evoked immediate increase in W and decrease in both SWS and REM sleep during baseline LD1:1 condition, while these changes ceased after SD. Moreover, the initial decrease seen in SWS after lights ON, turned to an increase in the next 6-min bin and this increase was stronger after SD. These alterations were caused by the change of the epoch number in W, but not in case of SWS or REM sleep. Lights OFF did not alter sleep–wake times immediately, except W, which was increased by lights OFF after SD. Present results show the complex interaction between light and homeostatic sleep regulation in the absence of the circadian component and indicate the decoupling of SW from the homeostatic sleep drive in LD1:1 lighting condition.

中文翻译：

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没有昼夜节律睡眠调节成分的稳态睡眠调节：短光暗周期对睡眠-觉醒阶段和慢波的影响

除了稳态和昼夜节律成分外，光本身在睡眠调节中也起着重要、直接和间接的作用。光通过调节昼夜节律发挥间接睡眠作用。暴露于短的明暗周期（LD 1:1，1:1 h 亮 - 暗）消除了昼夜节律睡眠调节成分，但光的直接睡眠效应可能占上风。本研究的目的是在大鼠模型中检查光与体内平衡对睡眠调节的影响之间的相互作用。使用 LD12:12 方案作为对照，在暴露于 LD1:1 条件的 Wistar 大鼠中检查了通过睡眠剥夺 (SD) 和慢波 (SW) 分析的自发睡眠-觉醒和稳态睡眠调节。慢波睡眠 (SWS) 和 REM 睡眠都得到增强，而清醒 (W) 在 LD1:1 中减弱。与 LD12:12 相比，6 小时总 SD 后的 SWS 恢复在 LD1:1 中更加强烈，并且在明亮时段 SWS 补偿增加。在这两种情况下，恢复期间的 Delta 功率增量是由 SW 数的增加引起的。与 LD12:12 相比，在 LD1:1 和 SD 之后的后半天基线期间看到了更多的 SW。在 LD1:1 的 SD 后，与暗时相比，亮时 SW 数的增加更大。在基线 LD1:1 条件下，灯打开引起 W 的立即增加和 SWS 和 REM 睡眠的减少，而这些变化在 SD 后停止。此外，灯亮后 SWS 中的初始减少转为下一个 6 分钟区间的增加，并且这种增加在 SD 后更强。这些改变是由 W 中纪元数的变化引起的，但不是在 SWS 或 REM 睡眠的情况下引起的。关灯不会立即改变睡眠-觉醒时间，除了 W，它在 SD 之后因关灯而增加。目前的结果表明，在没有昼夜节律成分的情况下，光和稳态睡眠调节之间存在复杂的相互作用，并表明在 LD1:1 光照条件下，SW 与稳态睡眠驱动脱钩。