The body goes through cycles called circadian rhythms that typically last about 24 hours. A human’s internal body clock, or circadian rhythm, regulates sleep and awake.
But these circadian rhythms can be disrupted by a number of things, leading to problems sleeping or otherwise.
Read on to find out how the circadian rhythm works, what circumstances can disrupt it, and what you can do to keep it in check for optimal health.
What is a circadian rhythm?
There is a daily, cyclical pattern of biological activity known as the circadian rhythm. This kind of cyclical pattern is found in all living things, from plants to mammals. They are necessary for life and can happen even if nothing else is there.
When it comes to humans, circadian rhythms are the patterns of behavior and physiological state that occur roughly every 24 hours.
What goes to sleep at night and what wakes up during the day Among the many well-known circadian rhythms, Trusted Source is particularly prominent. Humans, in general, feel sleepy at night and alert during the day. When individuals talk about a circadian rhythm, they typically mean this 24-hour cycle. Yet they go beyond just the quality of one’s slumber.
Human circadian rhythms also manifest themselves in the following ways:
- hormonal activity
- body temperature
- immune function
What Controls Circadian Rhythms?
The body’s circadian rhythms keep everything running smoothly and optimally 24 hours a day, every day. Not only do they assist certain animals sleep and feel secure in their shelters at night, but they also cause other creatures to be active at night and sleep during the day.
Many bodily functions in humans are regulated by circadian rhythms. The endocrine system, for instance, regulates hormones to match energy expenditures throughout the day, while the digestive system creates proteins to ensure that you eat at regular intervals.
The suprachiasmatic nucleus acts as a master clock in the brain, transmitting messages at regular intervals that profoundly affect the circadian rhythms of all the body’s systems.
How Does Circadian Rhythm Work?
The body’s processes are maximized at different times throughout the day thanks to the assistance of circadian rhythms. The Latin phrase “circa diem” literally means “around a day,” and is the source of our modern word “circadian.”
All living things have circadian rhythms. They aid in the proper timing of flower opening and closing and prevent nocturnal animals from emerging from their hiding places during the day, when they are more vulnerable to predators.
Humans have circadian rhythms that regulate the functioning of their bodies and minds. The gastrointestinal system generates proteins at regular mealtimes, while the endocrine system controls hormone levels to accommodate average metabolic needs.
The brain houses a master clock, also known as the circadian pacemaker, which is linked to the circadian rhythms that occur throughout the body. It resides in the hypothalamus, and more specifically in the suprachiasmatic nucleus (SCN). Clock genes in the SCN deliver signals to regulate activity throughout the body at various times of the day.
The SCN is extremely light-sensitive, and light is a crucial external cue that affects the messages transmitted by the SCN to coordinate internal clocks in the body. This is why the day and night play such an important role in regulating circadian rhythms. Light has the strongest influence on circadian rhythms, while other cues such as exercise, social interaction, and temperature can also alter the master clock.
Is a Circadian Rhythm the Same As a Biological Clock?
Circadian rhythms and other biological processes benefit from the timing provided by biological clocks. An internal body clock can cause what is known as a circadian rhythm, however not all internal bodies clocks have one. Plants, for instance, use a non-24-hour biological clock to adapt to seasonal shifts.
How Does Circadian Rhythm Affect Sleep?
Circadian rhythm is typically discussed in relation to sleeping patterns. One of the most obvious and significant instances of the significance of circadian rhythms is the sleep-wake cycle.
The master clock’s circadian rhythms are regulated by the exposure to light, which generates awareness and helps keep us awake and active during the day. The master clock starts secreting melatonin, a hormone that induces sleep, as soon as darkness falls, and it keeps sending signals to keep us asleep all night long.
As a result, our circadian rhythm helps us maintain a regular schedule of restorative sleep at night that fuels our productivity during the day.
What Does Circadian Rhythm Affect Besides Sleep?
Circadian rhythms, of which the sleep-wake cycle is only one example, are 24 hour internal clocks that play an important role in nearly all systems of the body.
Circadian rhythms have been linked to metabolism and body weight through their effects on blood sugar and cholesterol levels, though more study is needed to draw firm conclusions. The risk of psychiatric disorders like depression and bipolar disorder, as well as neurodegenerative diseases like dementia, may be affected by circadian rhythms.
Circadian rhythms have been shown to affect immune system function and DNA repair, both of which play a role in cancer avoidance. An emerging body of evidence suggests that circadian cycles affect the efficacy of anti-cancer treatments, and that novel medications may be able to use biological clocks to eradicate cancer cells.
What Happens When Circadian Rhythm Is Off?
When the body’s internal clock, or circadian rhythm, is thrown off, normal physiological processes are disrupted.
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.
Researchers have also found that obstructive sleep apnea (OSA), a sleep disease characterized by periodic pauses in breathing, may be caused, at least in part, by problems with the body’s natural 24-hour clock. Oxygen deprivation due to OSA results in frequent awakenings during the night.
Misalignment of the circadian rhythm can have far-reaching effects on sleep, increasing the likelihood of both insomnia and excessive daytime sleepiness. Given the importance of sleep to performance and wellbeing, circadian rhythm disruptions can have serious implications.
What Can Disrupt Circadian Rhythm?
The circadian cycle is susceptible to both temporary and persistent disruptions. Different forms of circadian rhythm sleep-wake disorders (CRSWD) have been recognized by specialists based on symptoms and root causes.
- Jet Lag Disorder: The name comes from the fact that transoceanic air travelers are particularly susceptible to the effects of this phenomenon, which occurs when a person rapidly crosses numerous time zones. A person’s sleep and energy levels are negatively impacted by jet lag until their circadian rhythm adjusts to the new day-night cycle.
- Shift Work Disorder: There might be serious disturbances to a person’s natural sleep pattern due to work commitments. When a person works shifts that require them to stay awake at night and sleep during the day, their normal sleeping pattern is disrupted and no longer corresponds with the local daylight hours.
- Advanced Sleep Phase Disorder: People who experience this type of disturbance typically report feeling sleepy in the early evening and awakening before dawn. People with advanced sleep phase disorder typically cannot alter their sleep schedules, no matter how much they would like to stay up later or sleep in later. This condition is more common among the elderly, affecting only about 1% of people in their middle years and beyond. An hereditary genetic predisposition is suspected in some cases of advanced sleep phase disorder.
- Delayed Sleep Phase Disorder: Night owls, who are notorious for staying up late and sleeping in late in the morning, are known to experience this type of disruption in their circadian rhythm. One or two out of every thousand persons experience this, but up to 16 percent of teenagers. Genetics, preexisting medical issues, and a person’s own actions are all potential contributing factors, but no one knows for sure what causes this.
- Non-24 Hour Sleep Wake Disorder: Those who are blind and so unable to use light cues to regulate their circadian rhythm are most likely to have this disorder. Their biological clock is still set to 24 hours, but they may lose an hour or more of sleep at a time.
- Irregular Sleep-Wake Rhythm Disorder: A person with this unusual disorder may sleep for only a few hours at a time, or they may nap often throughout the day. It’s often linked to diseases and injuries that hamper hypothalamic function, like dementia and TBI.
Circadian rhythm problems have a wide range of potential causes, as evidenced by this list. Circadian rhythms can be thrown off by activities like jet lag or shift work, which cause people to get less sleep than they need. However, in certain cases, the inability to receive or process environmental cues that govern the body’s master clock is the underlying cause of the condition. There may be a genetic component in some cases, or the root reason may be unidentified.
How To Maintain a Healthy Circadian Rhythm
While our circadian rhythm is under some genetic influence, there are steps we can do to improve how well we entrain our 24-hour sleep cycles.
- Seek out sun: The greatest circadian cue is bolstered by early-morning exposure to natural light.
- Follow a consistent sleep schedule: Your body’s ability to establish a regular circadian rhythm can be hampered if you keep shifting your bedtime or wake up time.
- Get daily exercise: A healthy internal clock is aided by regular activity during the day, making it simpler to drift off to sleep at night.
- Avoid caffeine: Caffeine and other stimulants might keep you awake and disrupt your body’s sleep-wake cycle. Caffeine should be avoided in the afternoon if sleeplessness is a problem.
- Limit light before bed: Nighttime exposure to artificial light has been shown to disrupt circadian rhythm. As sleep approaches, experts recommend turning down the lights and putting down electronic gadgets, and removing them from the bedroom entirely.
- Keep naps short and early in the afternoon: Naps, especially long ones, might delay bedtime and throw off your normal sleep pattern.
While taking these measures to enhance sleep hygiene can be helpful in sustaining a healthy circadian rhythm, it’s crucial to note that other measures may be required. Consult a medical professional if you have trouble sleeping, are sleepy during the day, or have trouble sticking to a regular sleep routine.