Circadian Rhythms Disorders and Sleep Phase Syndrome

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Some people tend to sleep early and wake up early in the morning and some cannot sleep early and as a consequence, wakes up late. These and other sleep-related problems are manifestations of a malfunctioning biological circadian clock and characterize several forms of Circadian Rhythm Disorder.

Circadian rhythms disorders, jet lag, insomnia, sleep phase, sleep disorders, 24 hr cycle, sleeping problem.

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Sleep forms part of human’s biological need to rest. As a person sleeps, the various physiological processes of a human body figuratively put into an apparent arrest and some parts of our system that were mostly exploited can be replenished for future use.

However, imagine a system so disrupted that our normal scheduling for sleeping and waking is totally altered. Some people tend to sleep early and wake up early in the morning and some cannot sleep early and as a consequence, wakes up late.

These and other sleep-related problems are manifestations of a malfunctioning biological circadian clock and characterize several forms of Circadian Rhythm Syndrome. Circadian activity is a unique by 24-hour period or cycles in which our body is physically patterned.

24-hour vs. 25-hour cycle

Earth rotates around the sun in a 24-hour cycle, so as our body functions in this 24-hour time schedule. All living organisms charismatically subscribe to this cyclic resting and activity patterns so that their body could function in sync with the environment in which they live.

Although humans externally operate under a 24-hour environment, research found that our body clocks evidently works significantly different than what we see in the environment.

It shows that the human body closely behaves as if it were under a 25-hour environment. Convincingly, humans’ reluctance to wake up at a required time and sleeping late at night probably explains this theory.

To compensate for this discrepancy, the body uses time “cues” to effectively counter-manage this asynchronous rhythmical. Setting an alarm helps us wake up at a designated time of the day and allows us to function as if it were under the 24-hour rhythmic schedule.

Dark vs. Light

Light and temperature provides the determining factor by which the body responds to the 24-hour activity period. The presence or absence of light mainly affects the part of the brain, which paces your bodily activities.

It was understood that the fundamental locus or location of our biological clock is the brain specifically in the suprachiasmatic nucleus (SCN) of the hypothalamus.

In complex animals like humans, hypothalamus forms part of the autonomous nervous system, which in part, controls the functions of organs that are not voluntarily controlled, hence involuntary. Involuntary, meaning, they are not governed by conscious will to act. These include breathing, heartbeat and intestinal digestion.

Eyes, Light and SCN

One interesting point to make is that the location of SCN is just above the optic chiasma (cross). Optic chiasma can is described as a location where optic nerve fibers meet and cross (chiasma-cross).

It is fitting to say that; the perception of light through the opening in the eyes triggers the wake/sleep patterns in humans since this is one way the organism receives such physical message.

As retina (a portion of the eye where initial image of an object is stored) traps light rays, an optic fiber relays the image to the brain via characteristic electrical pulses.

This unique sensory impulse is carried along the optic fibers to the occipital lobe (rear part) of the brain and is perceived as images. The proximity of the optic chiasma to the SCN perhaps provides the opportunity for the hypothalamus to “sense” the referred electrical impulses.

Forms of Circadian Rhythms Syndrome/Disorders

Circadian Rhythm defects can come many distinct forms depending on the amount and timing of waking up and sleeping. Others, as in the case of Seasonal Affective Disorder (SAD), result in the changes in the length of day and night.

People who tend to sleep at a later time of the day and wake up late as well are said to be exhibiting Delayed Sleep Phase Syndrome (DSPS). These people tend to develop insomnia, an abnormal inability to take adequate amount of sleep due to not being able to sleep at the right time of the night.

Still, other people, especially the elderly, are more likely to sleep early around 7:00 PM and consequently wake up early around 1:00 AM or 2:00 AM. This is a symptom of disrupted natural biological rhythms known as Familial Advanced Sleep-Phase Syndrome (FASPS).

The amount of a substance called melatonin is also perceived as a motivating factor in sleep-related disorders in humans. In a study among vertebrate mammals, melatonin is secreted in response to the absence of light.

This means more melatonin is secreted in the period of darkness and less in the presence of light. It presupposes the idea that melatonin is related to the 24-hour sleep/wake cycle of every human being.


With the knowledge gained in the preceding discussion, it can be assumed that the presence and absence of light affects our sleeping/waking schedule. With these in mind, keep yourself committed to your schedule to rest and sleep and set aside things, which are not really important.

Keep your room as dark and gloomy as possible, to make it easy for you to sleep. Colorful objects stimulate your senses and disrupt sleep. Keep it ventilated and air-conditioned.

Studies show that as we sleep, our body temperature drops and allows the neurotransmitter melatonin to be produced at a rapid pace.

Keep those things in mind and do not forget to seek medical help should your condition progresses.