© 2021 Condor, All Rights Reserved

The Consequences Of Circadian Rhythm Disorders

Sleep restriction or deprivation, regular exchange of diurnal habits for nocturnal habits, severe insomnia, irregular meal times and time zone changes are among the events that mess with our biological clock, promoting direct consequences on behavior throughout the day.

This dysregulation can cause symptoms such as excessive tiredness, loss of concentration, headache, irritability, stress and insomnia – just to name a few – and can even culminate in very serious illnesses such as heart disease, diabetes and depression. These are circadian rhythm disorders, which can be severe and be very harmful to our health.

In this article, we will mention some consequences of circadian rhythm disturbances. This is a serious and relevant matter, which deserves your full attention, and the search for medical help, if these disorders are robbing you of quality of life.

What is the circadian rhythm?

Also known as the circadian cycle, the circadian rhythm is nothing more than the period of about 24 hours on which a biological cycle is based. A series of events of our organism are synchronously organized in this period, being influenced by external influences and their respective consequences. A good example of this is our need to sleep during the dark phase and be awake during the day when the sun rises.

In order to understand what circadian rhythm is, it is necessary to highlight the concept of the word “rhythm”, which is, according to the Oxford Dictionary, “regular and periodic movement in the course of any process”. As we have already covered in a previous text about the circadian rhythm, natural events such as tidal rhythms, sunrise and sunset and moon phases have a stable rhythmicity throughout time, being present for thousands and thousands of years, and affecting the behavior of living beings.

In short, circadian rhythm synchronization is the process by which our bodies regulate the so-called “biological clock”. From the circadian expression, a series of events happens periodically and synchronized in healthy individuals, such as hormonal regulation, food frequency and sleep/wakefulness, among other physiological processes.

The importance of circadian rhythm

Daylight and its absence at night have a direct and decisive influence on our biological clock. This biological clock acts as an internal timing system, setting the “schedules” of our day and night activities, as well as our waking and sleeping states.

But that’s not all. The circadian rhythm also has a direct influence on blood pressure, on hunger, on body temperature, and also on the hormones that we produce and release via the bloodstream. That is, there is a direct influence on our entire metabolism and our behavior throughout the day.

Therefore, the circadian cycle has total interference in the release of cortisol, for example, which helps us to get out of bed in the morning, in the production of insulin – which helps us use the glucose obtained from food – as well as in the production of melatonin, essential for sleep time.

It is easy to understand that disorders are capable of causing hormonal imbalances that, if not treated, can be the gateway to infections, flu or even more serious pathologies, such as cardiovascular diseases and diabetes.

The 3 types of biological clock

Yes, there are three types of biological clocks; after all, people are not the same. People organize their lives around times to go to bed, wake up, work, eat and promote leisure activities, and this is not the same for everyone.

Isn’t it true that there are people who are much more productive in the morning, while others are more active during the evening, or at night? It is exactly because of the three types of biological clock, which are:

• Morning or day: these people like and prefer to wake up early, work very well in the morning and go to bed early. In general, they have more difficulty concentrating at night.

• Evening or night: unlike morning people, afternoon people produce much more at night, or even at dawn, concentrating their activities at these times. They usually have a more irregular sleep/wake cycle and have difficulty concentrating in the morning.

• Intermediaries: also known as indifferent, they can adapt to schedules more easily, with a preference between mornings and afternoons. Most of the world’s population is intermediate

What can cause Circadian Rhythm disorders

Some factors can influence the circadian rhythm, causing disturbances. The main ones are:

• Regular work at night;

• Pregnancy;

• Time zone changes;

• Use of certain medications;

• Sudden changes in routine;

• Sleep deprivation;

• Sleeping too late and waking up too late;

• Menopause;

• Parkinson’s disease;

• Alzheimer’s disease.

In addition to affecting sleep, these disorders can impair hormone production, change body temperature, interfere with metabolism and eating habits, which can lead to diabetes, obesity and depression, among other problems.

Professional categories most at risk of suffering circadian rhythm disorders

In general, workers who take alternate shifts or who work at different times than the standard period (9:00 am to 5:00 pm) are at greater risk of experiencing circadian rhythm disorders. Some of them are:

• All health professionals (that work shifts in hospitals);

• Drivers and pilots;

• Personnel working in the food sector (bakeries, for example);

• Cops;

• Firefighters;

• Security guards

Delayed sleep phase syndrome

This is a very common circadian rhythm disorder. People who suffer from this disorder have difficulty falling asleep, prefer to sleep later, and have trouble getting up early. Although they sleep and wake up at later times, these people generally have a normal quality of sleep. You can seek follow-up with a sleep medicine professional, who can apply cognitive behavioral therapy. To adjust your biological clock, it is recommended to manipulate your sleep schedules until you are able to establish a more suitable time. Another good tip is phototherapy treatment.

Advanced Sleep Phase Disorder

It is the opposite of delayed sleep phase syndrome. In this case, the affected person falls asleep and wakes up too early, which can also cause social problems. Often the person affected by this syndrome, also a very common circadian rhythm disorder, feels sleepy in the early or late afternoon. Phototherapy (using special lights as a form of treatment) can be indicated for these cases, as well as adjusting the bedtime, until adapted to the ideal time.

Irregular Sleep-Wake Rhythm

People affected by this disorder have an undefined circadian rhythm of the sleep/wake cycle, therefore an irregular cycle. The most common symptoms presented are drowsiness and intense insomnia, and the main causes are poor sleep hygiene, lack of sun exposure, sedentary lifestyle and even lack of social activities. As a form of treatment, it is necessary to establish a fixed time for sleep, in addition to the practice of regular physical activities.

Non-24-hour sleep-wake disorder

This disorder causes people to experience a longer-than-usual circadian cycle. This can cause insomnia and even excessive sleepiness. In general, the cause of this circadian rhythm disorder is lack of light, so blind people are more likely to develop it. The ingestion of melatonin at dusk can be used in the treatment.

Jet Lag Disorder

This disorder is transitory, and can last from two to 14 days, depending on the person’s time zones, age and physical capacity. It is naturally related to long-distance air travel. The affected person may experience excessive sleepiness and insomnia, as well as waking up several times throughout the night, but their endogenous circadian cycle is not abnormal. The problem is that the disorder is due to a conflict between the sleep-wake cycle and the need to establish a new pattern due to the different time zones.

People affected by this disorder may also present gastrointestinal discomfort, changes in memory and concentration, difficulty in coordination, weakness, dizziness, headache, tiredness, malaise and decreased appetite. As a treatment, it is necessary to perform sleep hygiene before, during and after the trip, adapting to the sleep/wake schedule of the destination. Some medications can be prescribed by your doctor.

Shift worker sleep disorder

It affects professionals who work in shifts, with sudden change of time. In these cases, the circadian rhythm cannot adequately adapt to these irregular times. Nurses can be an example of that, since they can work on shifts of up to 24 hours every three days.

The main symptoms presented by those affected by this disorder are insomnia and drowsiness, decreased vitality and performance, increased blood pressure, increases in gastrointestinal disorders and reproductive problems and also a higher prevalence of breast, colorectal and prostate cancer.

The treatment is not easy due to the worker’s schedule, who needs to comply with it on a daily basis. If symptoms cause a lot of discomfort and loss of quality of life, your doctor may prescribe stimulant or sedative medications and hypnotics.

The influence of circadian rhythm on our body weight

It is already clear that the circadian rhythm influences our need to eat at meal times, for example – especially at breakfast, lunch and dinner. What more recent studies have found is that the disruption of the circadian cycle can have consequences on our body weight.

At night, our body intensifies the release of melatonin through the pineal gland. If we are balanced and have a normalized functioning of this gland, melatonin will act directly on our sleep, on the cell renewal process, on inflammatory processes, on the modulation of the effects of stress, on female fertility, alleviating menopausal symptoms and even on burning of body fat.

Imbalances in our circadian rhythm, through sleep restriction or deprivation, can cause physiological changes in our body, including increased fat. According to the doctoral thesis of Dr. Bruno Halpern, from University of São Paulo (USP), entitled “The role of melatonin in the regulation of brown adipose tissue” (2018), melatonin has a fundamental role in the activation of brown adipose tissue (fat-burning cell) and in the burning of white adipose tissue (fat-storing cell).

Therefore, disturbances in the circadian cycle can have a direct consequence on our body weight.

Actigraphy and the treatment of sleep disorders

Sleep disorders are very common among the consequences of circadian rhythm disturbances. One way to follow the activity and rest cycles, with the capture, compilation and processing of information to study the rhythm of sleep and wakefulness is the use of actimetry, also known as actigraphy.

Actigraphy is performed using the actigraph, which in most models resembles a wristwatch, attached to the patient’s non-dominant arm. The actigraph collects and compiles all the person’s movement by means of accelerometers, and the most modern devices also offer temperature and light sensors, among other features, enabling an even deeper analysi

It is worth pointing out that actigraphy detects sleep and circadian rhythm disturbances, assessing sleep quality, the time the person remains in bed and sleep episodes during the day. The actigraph is widely used for studies in sleep medicine, psychiatry, occupational medicine, behavioral psychology and other areas where circadian rhythms play a fundamental role in the study of disorders.


The consequences of circadian rhythm disturbances can be severe and absolutely detrimental to our health. They can even progress to depression, diabetes, heart disease or even cancer. Therefore, they need to be treated at the slightest sign of compromise in our quality of life.

Treatments will vary from case to case, but in general it is necessary to promote changes in our lifestyle, such as regular physical exercise and regular sleep. Some medications may also be prescribed by your doctor. The actigraph can be highly recommended for further researching both sleep disturbances and circadian rhythm disturbances.

Para preveni-los é preciso evitar substâncias que afetam o sono, como cafeína, álcool e nicotina (ao menos não ingeri-los após as 16hs), deve-se consumir bebidas frias (principalmente água e chás gelados), manter um horário regular de sono, tomar banho de sol e evitar luzes artificiais ao entardecer e durante a noite (principalmente a chamada luz azul, de computadores e celulares, e a luz de lâmpadas de LED brancas).

Research on circadian rhythms is increasingly evolving. The study “A world first in circadian clock manipulation” by the Institute of Transformative Biomolecules at the University of Nagoya, for example, discovered two compounds that prolong the circadian cycle period and produced a reversible method for controlling the rhythm period. These researches will certainly help in the treatment of circadian rhythm and sleep disorders.