The Four Stages Of Circadian Rhythms

This is the last stage in our sleep cycle - the deepest stage which also lasts the longest. Each sleep phase is a slight bit deeper. This means that you are in each phase a little longer than the previous one. It's in this stage - during REM sleep - that dreaming occurs and most of the recuperative functions associated with sleep take place.

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.

Have you ever not gotten enough sleep, or cut your sleep short for a class? Show of hands? Alright, well today I will be speaking with you about a subject that is near and dear to all of our hearts. Today I will be talking about sleep, specifically about REM sleep. First off does anyone know what the initials REM even stand for? REM stands for rapid eye movement, and it is the stage of sleep in which most dreams occur. It gets its name from the way your eyes move back and forth in this stage. Though those movements are slower than how your eye would move when you are awake. During a typical night, you cycle between REM and non-REM sleep, but spend the majority of your time asleep in non-REM.

There are distinctive stages of sleep REM sleep and non-REM sleep and about every ninety minutes we cycle through four recognizable sleep stages (Myers D 2014). Non-REM sleep consists for 3 different stages and during each stage it contains its own purpose. Stage one occurs for about 10 minutes and is when a person is lightly sleeping and can be woken up very easily (Mastin 2013). Muscles are still active and movement occurs more frequently such as twitches and the eyes roll around at a slow pace and breathing and heart rates slow down (Mastin 2013). Stage two happens between 45-50 percent of the night at different intervals (Mastin 2013). Muscle activity decreases and it is harder to wake up during this stage; if sounds are heard they are no longer able to make sense of them (Mastin 2013). The last stage: stage three which is also called delta

The brain activity during REM sleep is mainly mixed brain waves consisting of theta, alpha and beta waves. This is also the point in a sleep cycle where the body is basically rigid. The brain has shut off all muscle movements other than the ones that keep you alive. This stage is a prime example of how the brain is busy while we are sleeping, “REM sleep begins with signals from an area at the base of the brain called the pons. These signals travel to a brain region called the thalamus, which relays them to the cerebral cortex – the outer layer of the brain that is responsible for learning, thinking, and organizing information. The pons also sends signals that shut off neurons in the spinal cord, causing temporary paralysis of the limb muscles”(Brain Basics). Being that REM sleep deals with learning, scientists believe this is the reason infants sleep a large amount of time and also why they are more susceptible to being woken up by the slightest noises. Since this stage of sleeping has a great deal of dreaming and brain involvement some scientists believe that dreaming is the brain’s way of sorting out information it receives during sleep, creating a “story” out of what it gathers. REM sleep could be considered as a work out for your brain, helping us to make sense of what we experience throughout our

Chronotype (CT) is part of the circadian routine and it is defined as an individual’s inclination in rise and sleep timing (Horne & Ostberg, 1977). Chronotypes comprise three different groups; morning, intermediate, and evening group (Adal et al, 2012). Specifically, the early group rise and sleep early, while individuals who belong to the evening group rise and sleep later than the morning group, whereas the intermediate group does not follow a specific pattern (Adal et al, 2012). Interestingly, around 40% of the individuals belong to one of the two poles, morning or evening group (Adal et al,

With this in mind, a person’s heart rate slows, and they begin to rest and recharge after a long day. When this person finally dozes off, they undergo cycles of non-REM and REM sleep. Non-REM sleep comes early in sleep and contains deeper, more restful sleep. Dream filled REM sleep comes late in the night and when all dreams occur. Dreams in REM sleep can last anywhere from a few seconds to forty-five minutes long. The transition between the two cycles happens at the same time for each person, regardless of bedtime. The time of this switch between cycles differs for each person. This is the reason for not forcing sleep. This results in a healthy balance of non-REM and REM sleep balance

Sleep consists of many different 90-minute cycles. These cycles are: alpha waves, NREM-1, NREM-2, NREM-3, and REM sleep. The first stage of sleep is known as the alpha waves. Alpha waves are “relatively slow brain waves of a relaxed, awake state” (Myers, 2017, p. 55). During the alpha waves stage the person is not yet asleep, but is laying calmly with his or her eyes closed. Eventually the person falls asleep, without being consciously aware of it, and moves into stage two of sleep.

3. Wintering over is a syndrome that 50% of the Antarctic inhabitants experience during the winter. This suggests that:

This stage is believed to help people enter deeper stages of sleep (4). Stage 3 sleep consists of 20-50 percent delta activity and stage 4 sleep of more than 50 percents delta activity (4). Stages 3 and 4 are characterized as being slow wave sleep in addition to being the deepest levels of sleep. Approximately 90 minutes after being asleep, people enter rapid-eye-movement (REM) sleep (4). REM sleep consists of rapid eye movements, a desynchronized EEG, sensitivity to external stimulation, muscle paralysis and dreaming (4).

Have you ever wondered what is happening while a person is sleeping? “Sleep is the word we use to define both a biological state and a behavioral state in which we are quiet and relatively unresponsive to external stimuli” (Larson 1990). Measured when sleeping, brain waves have been identified into several distinct stages. Everyone experiences four stages of the sleep cycle, including REM (Larson 1990). This topic really interested me because it is something that every human goes through and it cannot be eliminated from a person’s life. This topic really catches my attention because everyone can experience the effects of sleep deprivation and it does not just occur in one specific person. This topic is significant to me because my grandfather has narcolepsy, a sleep disorder.

Circadian rhythm is most known for the effect on sleep and wake, but it also affects eating, hormone secretion, urination, and much more (Kalat, 2013). Circadian rhythms are endogenous, which means they are generated from within the body. When broken down into its latin roots “circum” and “dies”, circadian means about a day. This name was coined as animal circadian rhythms last about a day, or around 24 hours (Kalat, 2013). Though rhythms are around 24 hours, each individual differs in their exact rhythm. This can be seen in the difference between “morning people”, who are alert and awake early in the day, and “night owls”, who awaken at a slower pace and reach their peak alertness later in the day (Taillard, Philip, Coste, Sagaspe, & Bioulac,

NREM (non-rapid eye movement) sleep is the light and deep stages of sleep “initiated by withdrawal of neurotransmitters from the reticular formation and by the inhibition of arousal mechanisms in the cerebral cortex.” The reticular formation found in the brainstem is primarily responsible for generating REM sleep, and NREM sleep is produced by projections from the reticular formation and other areas of the mesencephalon (midbrain). Normal sleep happens in cycles of NREM and REM sleep. When a person falls asleep, he first enters into a light sleep and then progresses into increasingly deeper stages of sleep (NREM cycle) for about 90 mins, followed by the initial stage of REM sleep, the two cycles alternating throughout the night. For people suffering from narcolepsy, sleep begins immediately with REM sleep and portions of REM happens involuntarily throughout the waking hours. As mentioned earlier, REM sleep is when muscles are paralyzed and when dreams take place, explains the associated symptoms of cataplexy, paralysis and hallucinations (McCance & Huether, 2014; "National Sleep Foundation,"

Circadian Rhythms are controlled by the suprachiasmatic nucleus (SCN), a group of cells found in hypothalamus. The SCN allows the body to adapt day-night changes through the release of melatonin which rises at night and falls in daytime. Melatonin treatment is used to fix desynchronized

The next circadian rhythm sleep-wake disorder is non-24-hour sleep-wake rhythm which the sleep time shifts a little later every day. One's sleep and wake up time continue to move later and later every day which can lead the sleep times to go in and out of the alignment with the other people as weeks go by. Shift work is the disorder when one has to be at work when the body wants to sleep. Then when one has to sleep, the body expects to be awake. This disorder causes one to have trouble sleeping or be severely tired. One also might not get enough sleep and the quality of sleep may be poor which can make them feel fatigued or exhausted. The last one is jet lag which occurs when one travels across the multiple time zones and has trouble adjusting