Updated at: 06-10-2022 - By: Jane

Some biological cycles, known as circadian rhythms, repeat every 24 hours. In humans, circadian rhythms cause physical and mental changes in the body, including feelings of wakefulness and sleep.

However, circadian rhythms can be disrupted by a number of factors, which in turn can cause sleep problems and other health problems.

Continue reading to find out how the circadian rhythm works, what circumstances can disrupt it, and what you can do to keep it stable for optimal health.

What is a circadian rhythm?

Large clock at train station with people walking around.

A circadian rhythm is a natural processTrusted Source that takes place throughout every day. These rhythms take place everywhere, occurring throughout the natural world, such as in plants and other animals. They are essential to organisms and occur even in the absence of outside factors.

Each and every day, the body undergoes a natural process known as a circadian rhythm. Rhythms like these can be found in all forms of life in nature, from plants to animals. They are necessary for life and can happen even if nothing else is present.

Every living thing on Earth follows a daily pattern known as a circadian rhythm, which occurs naturally at the same time each day. These cycles can be found in every living thing, from plants to animals. They are required for survival and can take place even when no external stimuli are present.

Human circadian rhythms also manifest in the following ways:

  • hormones in motion
  • ambient heat production
  • digestion
  • immune system

What Controls Circadian Rhythms?

The body’s circadian rhythms keep everything running smoothly and efficiently 24 hours a day, every day. But they aren’t just for people; some animals use them to sleep better at night and feel more secure in their dens, while others use them to stay up and hunt at night and sleep during the day.

Many bodily functions in humans are regulated by circadian rhythms. The endocrine system, for instance, controls hormone levels to balance food intake and energy expenditure.

A master clock in the brain called the suprachiasmatic nucleus greatly influences the circadian rhythms of all the body’s systems by delivering signals at the right times.

How Does Circadian Rhythm Work?

Circadian rhythms work by helping to make sure that the body’s processes are optimized at various points during a 24-hour period. The term circadian comes from the Latin phrase “circa diem,” which means “around a day.”

The body’s processes are maximized at different times of the day thanks to the assistance of circadian rhythms. The Latin phrase “circa diem” translates to “around a day,” from which we get the term circadian.

The brain has a master clock, also known as the circadian pacemaker, which regulates the circadian rhythms experienced by the rest of the body. It resides in the hypothalamus, and more specifically in the suprachiasmatic nucleus (SCN). Clock genes in the SCN send signals throughout the body at various times of the day to control its activities.

A key external trigger that affects the signals transmitted by the SCN to coordinate internal clocks in the body is light, which the SCN processes very quickly. This is why the day and night are so important in regulating circadian rhythms. Light has a greater impact on circadian rhythms than any other environmental cue, including exercise, social activity, and temperature.

10 Things You Didn't Know About Your Circadian Rhythm | Prevention

Is a Circadian Rhythm the Same As a Biological Clock?

Circadian rhythms and other internal activities benefit from the timing provided by biological clocks. Even though circadian rhythms are often the result of biological clocks, this is not always the case. For example, plants use a non-24-hour biological clock to adapt to seasonal shifts.

How Does Circadian Rhythm Affect Sleep?

Most discussions of circadian rhythm revolve around sleep. One of the most obvious and significant instances of the significance of circadian rhythms is the sleep-wake cycle.

During the day, our bodies are able to stay alert and productive because the master clock receives light signals triggering the release of these chemicals. When nighttime arrives, the master clock signals the body to begin producing melatonin, a hormone that aids in falling asleep, and to maintain sending these signals so that we remain sleeping all night long.

Our circadian rhythm helps us maintain a regular schedule of restorative sleep at night so that we can be more productive throughout the day.

What Does Circadian Rhythm Affect Besides Sleep?

These 24-hour internal clocks play an important role in nearly all systems of the body, including the sleep-wake cycle, which is one of the most prominent circadian rhythms.

Circadian rhythms have been linked to metabolism and weight by the management of blood sugar and cholesterol, and more information is being uncovered regarding this connection all the time. The risk of psychiatric disorders like depression and bipolar disorder, as well as neurodegenerative diseases like dementia, may be affected by circadian rhythms.

Cancer prevention activities involving the immune system and DNA repair may be profoundly impacted by circadian rhythms, as has been observed. Emerging evidence suggests that circadian cycles can affect the efficacy of anti-cancer treatments, suggesting that new medications may be able to harness biological clocks to destroy cancer cells.

What Happens When Circadian Rhythm Is Off?

When the body’s internal clock, or circadian rhythm, is disrupted, normal operation of the body’s systems is compromised.

Serious sleep issues might arise from an off circadian cycle. A person may have trouble falling asleep, wake up frequently throughout the night, or get up earlier than desired in the morning if the body’s internal clock isn’t sending the right signals. Sleep duration can be shortened, and sleep depth, continuity, and quality can all suffer if their circadian cycle is thrown off.

Additionally, obstructive sleep apnea (OSA), a sleep disease characterized by periodic pauses in breathing, may be exacerbated by changes in circadian rhythm, according to research. Sleep apnea (OSA) causes significant drops in blood oxygen levels and frequent awakenings throughout the night.

Insomnia and excessive daytime sleepiness are only two of the many sleep problems that can result from a disrupted circadian clock. There are typically serious repercussions when a person’s circadian rhythm is wrong because of the crucial role sleep plays in productivity and general health.

What Can Disrupt Circadian Rhythm?

Circadian rhythm disruptions can have either a temporary or permanent effect on an individual. Many distinct forms of circadian rhythm sleep-wake disorders (CRSWD) have been recognized by specialists based on their symptoms and root causes.

  • To put it simply, jet lag is a condition that affects persons who transit many time zones in a short period of time, such as those who take transoceanic flights. Jet lag is characterized by difficulty sleeping and weariness until the body’s circadian clock adjusts to the new day-night cycle.
  • Having to work irregular hours can seriously throw off a person’s circadian cycle, a condition known as shift work disorder. With shift employment, one’s sleep schedule is directly at odds with the local daylight hours because of needing to work through the night and sleep during the day.
  • Individuals affected by this disorder experience fatigue in the early evening and an early morning awakening. People with advanced sleep phase disorder typically cannot adjust their sleeping and waking schedules even if they wanted to. This condition is more common in the elderly than in those of middle age or younger. A genetic predisposition to developing advanced sleep phase disorder has been suggested in some situations.
  • Those who are “night owls,” staying up late and sleeping in late, are more likely to suffer from Delayed Sleep Phase Disorder, a form of circadian rhythm disruption. Although it only affects 1-2 people per 1,000 in the general population, it can affect up to 16% of teenagers. The specific reason is unclear, however it could have something to do with a person’s genes, their physiology, or their actions.
  • People who are blind and therefore cannot use light cues to regulate their circadian rhythm are more likely to experience non-24-hour sleep-wake disorder. Their biological clock is still set to 24 hours, but they may lose an hour or more of sleep at a time.
  • People with the uncommon condition known as irregular sleep-wake rhythm disorder may sleep for only a few hours at a time, or may wake up frequently throughout the day. It’s often linked to diseases and injuries that hamper hypothalamic function, like dementia and TBI.

As this list demonstrates, there are diverse causes of circadian rhythm disorders. Some circadian disruptions are related to individual behavior, such as for travel or work, that puts sleep schedules out of whack with normal daylight exposure. Still other diseases have their roots in an underlying problem that prevents a person from picking up on, or correctly interpreting, environmental cues that set the body’s master clock. Some conditions have unknown or perhaps hereditary origins.

How To Maintain a Healthy Circadian Rhythm

Circadian rhythm problems can have a wide range of causes, as seen by this list. Individual activities, such as that required for travel or employment, can disturb the circadian clock by throwing off the regular rhythm of the body’s sleep-wake cycle in response to the 24-hour day. Various other illnesses result from a malfunction somewhere in the body that prevents it from picking up or correctly interpreting environmental cues that keep the master clock in check. Possible or actual genetic factors in play in some cases.

Clock visual displaying a schedule of things to do throughout the day to maintain a healthy sleep/wake cycle
  • Seek out sunlight: early morning exposure to natural light strengthens the strongest circadian cue.
  • Maintain a regular bedtime routine: The body’s capacity to establish a regular circadian rhythm is hampered if the time you go to sleep and wake up each day is constantly changed.
  • Exercise on a regular basis; doing so can aid in regulating your body clock and making it simpler to wind down at night.
  • Stay away from caffeine because it is a stimulant and might disrupt your sleep-wake cycle. While the effects of caffeine on sleep patterns vary from person to person, in general, consuming caffeine after noon can cause insomnia.
  • Reduce your exposure to artificial light in the hours just before bed. In the hours before night, experts recommend turning down the lights and putting down electronic gadgets, as well as keeping those devices out of the bedroom and away from the mattress.
  • Avoid taking long, late-afternoon naps; doing so will delay nighttime and throw off your sleep routine, so napping early in the afternoon is recommended.

These measures to enhance sleep hygiene can be helpful in promoting a normal circadian rhythm, but further measures may be required in some cases. Consult a medical professional if you have trouble falling or staying asleep, if you find yourself falling asleep during the day, or if you have trouble maintaining a healthy sleep routine.

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