Sleep Is A Quintessential Importance Of Sleep

I. Introduction

Sleep is of quintessential importance in our daily lives. Prolonged sleep deprivation can result in decreased immune system and in the worst case scenario death. As everyone can relate to, our sleep-wake cycle is relatively regular and stable, and there is a reason for our regular biological cycles: the suprachiasmatic nucleus (SCN). In our body, multiple biological clocks regulate circadian rhythms like our sleep-wake cycle and rhythms of hormonal release. Within the hypothalamus, the suprachiasmatic nucleus (SCN) contains the master clock that regulates the peripheral circadian clocks in the brain to prevent them from going out of sync with each other. The SCN also receives information from the retina for light entrainment and thus maintains the whole system in synchrony with the light-dark (LD) cycle. It has been the central dogma in the field of circadian biology that light is the primary zeitgeber, cue that entrains the circadian rhythm. Many studies show that daytime neuronal activity of the SCN and light-induced neuronal activity of the SCN inhibit locomotor activity in nocturnal rodents. However, several studies show that the food anticipatory behavior (FAA), which is induced by limiting food to a few hours a day, can be zeitgeber that supersedes all other cues, including light. Rodents can anticipate a predictable daily mealtime by entrainment of circadian oscillators. Studies show that this anticipatory behavior does not require the master circadian clock within the SCN and this has led to the hypothesis that there are food-entrainable oscillators (FEOs) in the brain responsible for the anticipatory behavior. However, the circadian oscillators responsible for the FAA are still unknown. In this paper, I ...

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...may not seem practical, it could shed some new light on the location of FEOs. Furthermore, more tests need to be done using different clock genes in order to determine if DMH is truly involved with FAA or simply downstream to other circadian oscillators that determine the FAA. If there are actually multiple FEOs in play, as proposed by Feillet et al. (2008), then there needs to be experiments combining lesions in multiple sites to produce impairments of FAA (Feillet and Mendoza, 2007). Again, because the answer is open to endless possibilities, I also participated in the research trying to locate the FEOs. However, my results did not yield any significant rhythms in the DMH when we performed in situ hybridization targeting the clock gene Baml1. Upon reading these articles, maybe a future research direction, even for me, will to consider FEOs other than the DMH.