Enzyme Responsible For Regulating The Human Circadian Clock

14. Evolutionary theories often emphasize that humans have adapted to their physical environment. One such theory hypothesizes that people should spontaneously follow a 24-hour cycle of sleeping and waking—even if they are not exposed to the usual pattern of sunlight. To test this notion, eight paid volunteers were placed (individually) in a room in which there was no light from the outside and no clocks or other indications of time. They could turn the lights on and off as they wished. After a month in the room, each individual tended to develop a steady cycle. Their cycles at the end of the study were as follows: 25, 27, 25, 23,24, 25, 26, and 25.

Circadian rhythms occur every 24 hours; an example of a circadian rhythm is the sleep-waking cycle. We are diurnal animals who are active during the daytime and asleep at night, other animals are nocturnal they are active at night but asleep during the day. The circadian rhythm depends on the interaction of physiological and psychological processes to be tuned into the sleep-waking cycle so energy is provided when needed. As diurnal humans we have a fairly stable sleep pattern with the time we go to sleep and the time we wake up, this consistency suggests an internal mechanism controls sleep, endogenous pacemaker. However, this can be overridden by external factors, exogenous zeitgebers.

Russell Foster is a British professor and a circadian neuroscientist at Brasenose College. He studies the sleep cycles of the brain. He and his group were credited for discovering photosensitive ganglion cells in the mammalian retina. This discovery will help to find more information about the circadian rhythm system. In 1980, Foster graduated from the University of Bristol with a degree in Zoology. He has earned many awards for his work and is also the author of a few books.

Humans have a natural rhythm of 25 hours of sleep and wakefulness, in order to reset this the brain plays an important role with the suprachiasmatic nucleus which is a cluster of neurons in the medial hypothalamus of the brain. The SCN

It is no secret that, similar to other animals, sleep is one of the most important things for a human being’s overall health. According to Watson and Breedlove, there are four main biological/neurological functions of sleep: energy conservation—the body uses less energy when it is asleep through what is called slow-wave sleep (SWS) by doing things such as reducing body temperature and slowing respiration; niche adaptation—the environmental happenings to which organisms are adapted to; body restoration—it restores materials used during awake hours; and memory consolidation—SWS and REM sleep help the brain consolidate memories from the previous day (2012).

Circadian rhythms are the bodies' biological internal clocks encoded within us during a 24 hour cycle interval that accommodates to our body’s natural fluctuations in a physical, mental, behavioral, and physiological form and is prominently influenced and modified in accordance to marginal potencies and stimuli reflective of probable and irrepressible variables in our natural world that can be used as the determinant for an individual’s specific developmental, communicative, and interactive compositions.

For melatonin to be effective at inducing sleep, it must be released two to three hours prior to succumbing to stage one of sleep. In the individual with no exposure to light stimulus during this time, the retina will send impulses to the suprachiasmatic nucleus in the hypothalamus and travel via superior cervical ganglia to the pineal gland. When the postganglionic sympathetic fibers synapses with the pineal gland, a release of norepinephrine initiates melatonin production in the pineal gland. The melatonin is received by MT1 receptors and acts to inhibit activity in the suprachiasmatic

In life, we all encounter those night where we can’t seem to get to sleep. This can be due to insomnia or having a lot of things to do and little time to do them. During college and afterwards people will begin to deal with a lack of sleep more and more as they gain more responsibilities. I’ve always heard it’s not good to go without sleep and I agree with this thought. This was confirmed when we had a lecture on consciousness. We discussed how our sleep and wake schedule, biological clocks, bodily functions, etc., are controlled by circadian rhythms (Truelove, 2017).

The pineal gland also plays a key role in regulating animal circadian rhythms, which vary across species. Melatonin is synthesized from serotonin by N-acetyltransferase. In mammals, N-acetyltransferase activity is stimulated in the CNS by sympathetic nerves stemming from the superior cervical ganglion, whereas in birds, the N-acetyltransferase “control switch” appears to lie within the gland itself (Deguchi, 1979).

Darkness is the trigger of the creation and secretion of melatonin and when there is light, melatonin creation levels drop extremely low and the melatonin produced is inhibited from being release. Generally for humans, melatonin increases around 9 p.m. to 10 p.m., peaking from 2 a.m. to 4 a.m., however each person will have their own pattern that their body follows (Blachford & Krapp, 2010). The secretion and production of melatonin reflects a circadian

The Monk and Buysse (2014) study looked at the interaction of an individual’s Morningness or Eveningness preference in relation to their sleep quality and duration. It had previously been established that sleep patterns progressively change upon aging (their chronotype) (i.e. their time to bed and time of awakening are both earlier). It would be interesting to apply the co-sleeping condition with specific nocturnal animals (e.g. cats or hamsters) to see if the animal’s nocturnal activities influence sleep quality and

Melatonin is a regulator of sleep wake cycles in all organisms. Furthermore, it is synthesised in the pineal gland and begins as an amino acid tryptophan. This amino acid is converted to serotonin and then metabolized into melatonin by the N-acetylation of 5-HT preceded with the addition of a methyl group at the hydroxyl position of the molecule via two enzymes called hydroxyindole-O-methyltransferase (HIOMT) and N-acetyltransferase (AANAT) (Foulkes et al. 1997; Schomerus and Korf 2005). After those steps melatonin has been synthesised and will begin to affect the sleep wake cycle of the species.

The test subjects of this experiment are sixty male Wistar rats [1]; they are bred and will be kept under a normal light-dark cycle. They will be kept in cages that are at a constant temperature of 25 °C. Water and food will be provided to them for the length of this experiment. Before commencing the experiment, the rats are allowed a week to become accustomed to the facility. After they have become 8 weeks of age, the rats are randomly placed in two groups, one that is exposed to a 12 hour light: 12 hour dark cycle (n=30 per group) and another that is exposed to a 12 hour light:12 hour dim light cycle (n=30 per group). The rats will be examined under experimental lighting for 3 weeks. The intensity of the light will be measured using a Traceable Dual Display light meter [1].

In the article “Shedding light on the day-night cycle”, many new researchers found different rhymes encoded to their daily life. Scientists at Washington University School of Medicine discovered different ways to test groups of neurons based on keeping time that will make them be on the same clock. As we know, life on earth is followed by the rising and setting of the sun. Using based knowledge, there are many night owls and morning risers. Stated in the article, “it is important to understand how fundamental timing information is translated into actual neuronal signals in the brain that are controlled by daily rhythms, including rhythmic behavior” (Paul Taghert). Daily cycles are known as circadian clocks. The circadian clock is based on evolution and uses a small amount of proteins which goes up and down by controlling your manner once a day. In the article, scientist do a study based on fruit flies. Liang talks about performing brain scans on live fruit flies every ten minutes for 24 hours. Every fly brain is behaviorally active 150 times in the morning and in the evening. Scientists are improving new tools to help one to identify signals and understand the control timing in the brain in other species.

Aside from noticing night and day and clocks our body has its own system to tell us when to sleep and when to wake, our circadian rhythm. The human body naturally runs on a twenty five hour clock, so living on a twenty four hour schedule is often hard on the body because it loses an hour each day. On top of this natural loss most people do not get the right amount of sleep each night which can cause a whole host of problems. This is part of