Circadian Rhythm Disorders- Sleep Studies
The human body is designed in a controlled, disciplined way where a 24-hour clock is set, controlling various activities and functions of your body. This clock is known as Circadian Rhythm. Hormone production, cell regrowth, and metabolism, etc., are linked to this circadian cycle. According to the American Academy of Sleep Medicine (AASM) International classification of sleep disorders, circadian rhythm disorder occurs because of variation to the body's master clock or misalignment between the clock and a person's external environment. In this way, our body's biological processes are interrupted.
The body systems with the most prominent circadian variations are:
- Sleep-wake cycle
- Temperature regulation system
- Endocrine system
There are particular genes in the DNA that function to control your circadian rhythm called circadian clock genes. Your body aligns the sleep-wake cycle with the help of environmental cues like light and dark, the timing of food, or physical activity. The first thing affected by the disruption of your cycle is obviously the quality of sleep. You may find it hard to sleep, which in the long run interferes with your daily activities.
Types Of Circadian Rhythm Disorders
According to the classification of AASM, the different types of circadian rhythm disorders are as follows:
- Advanced Sleep-Wake Phase Disorder: It is characterized by tenacious early evening sleep onset time, i.e., predominantly between 6 pm to 9 pm while wakSleep-wake cycleing up as early as 3 am to 5 am.
Common features:
- It interferes with your daily activities, be it social, work-related, or school, due to complaints of insomnia and early morning awakening.
- It is most commonly seen in the elderly.
- It might run in families.
- Delayed Sleep-Wake Phase Disorder: One of the most common disorders related to sleep in today's time where a person's sleep-wake cycle is pushed beyond more than 2 hours to a regular sleep schedule. It leads to difficulty falling asleep at night and then getting up in the morning. Such people are known as "evening chronotypes" or "night owls," with a prevalence rate in young adults and teens from 7 to 16%.
Common features:
- It makes a person more active and creative at night.
- It leads to anxiety and daytime fatigue.
- It makes a person lazy at getting up in the morning, and ultimately they perform poorly, especially in the daytime.
- It is common in young adults and adolescents.
- It may also run in families.
- Irregular Sleep-Wake Rhythm Disorder: It is characterized by inconsistent and undefined sleep patterns during which you may take several naps during the 24-hour cycle.
Common Features:
- Ongoing chronic insomnia
- Excessive sleepiness
- It is most commonly observed in people suffering from neurological conditions like dementia, Parkinson's, or Alzheimer's disease.
- It is also seen in children with developmental disorders.
- Jet Lag Disorder or Rapid Time Zone Change Syndrome: It is a condition when a person's internal clock is disturbed due to an air flight that passes over multiple time zones. Although it is a temporary sleep disturbance, even then, the fatigue that follows makes it difficult to adjust and function in the new time zone. The symptoms appear one to two days after the flight and last up to a week or two. Eastbound travel is more difficult to cope with than westbound since it is easier to delay sleep than advance.
Common Features:
- Insomnia
- Change in appetite and gastrointestinal functions
- Daytime fatigue
- Discomfort and mood disturbance
- Non-24-hour Sleep-Wake Syndrome or Free Running Disorder:
In this condition, typically, people tend to have a longer than 24-hour circadian rhythm; hence, sleep time might gradually become more delayed. A person's regular sleep-wake cycle is changed with a delayed time of 1 to 2 hours every day. The main reason behind this syndrome is minimum light exposure, and therefore, it is primarily common in blind people. Their eyes cannot transmit as many light signals to the brain, which leads to confusion regarding the time of the day. Around 50 to 80% of blind people report sleep disorders.
- Poor sleep quality
- Daytime sleepiness
- Shift Work Disorder: People who often rotate shifts or work at night. It creates a conflict with the body's natural circadian rhythm, and they get 3 to 4 hours less sleep than an average person.
- Insomnia or sleeplessness
- Intense fatigue
- Gastrointestinal problems
- Decreased sex drive
- Weight gain
- High blood pressure
Internal And External Causes Of Circadian Rhythm Disorders
There are several factors responsible for causing sleep problems and lead to circadian rhythm disorder. Following are some of the factors which might trigger a circadian rhythm disorder:
- Frequent work shift changes
- A genetic condition affecting the brain and hormones, for example, a genetic disorder that affects the level of melatonin hormone production known as Smith-Magenis Syndrome
- Frequent changes in sleep or wake-up time
- Blindness and low exposure to the sun
- Pregnancy
- Medicines
- Mental health conditions like Parkinson's
Diagnosing Circadian Rhythm Disorders
The diagnosis of sleep disorders is challenging and mostly requires a sleep specialist to perform proper consultation. A person might need a consultation in the following cases:
- You are unable to fall asleep.
- You wake up with morning fatigue.
- You haven't slept properly for over a month leading to memory issues, trouble concentrating, and severe daytime sleepiness.
Medical History and Physical Exam:
Your doctor will ask specific questions regarding the signs and symptoms, personal and family health history. He then performs a physical examination.
Diagnostic Tests:
Your physician might ask to perform the following tests to confirm a diagnosis:
- Sleep diary for one to two weeks to help a person track the time of sleep.
- Actigraphy is basically a method to measure your sleep-wake activity in which a wristwatch-like device or a motion sensor is used for 3 to 14 days.
- Sleep studies are tailored to address how the body responds to sleep problems and how well you sleep overnight.
- Measuring the levels of melatonin and cortisol in your blood or saliva
Rule out other conditions
It is essential to find out in detail about the causes of symptoms presented at the consultation. Your doctor might ask these questions for a proper diagnosis:
- Inquiring about use of drugs, alcohol, and caffeine intake or exposure to light at odd times.
- Any underlying health condition which prevents a good night sleep due to pain
- Examine airway and tonsils
Treatment Of Circadian Rhythm Disorders
Treatment for circadian rhythm disorders aims to improve sleep quality and reset the rhythm to align with the environment. The treatment plan is scheduled according to the degree and type of condition. Many treatments involve a combination of approaches emphasizing the significance of good sleep hygiene.
Most common treatments include the following:
- Healthy Lifestyle:
It includes scheduling naps and developing good sleep habits by maintaining regular sleep-wake time. Perform regular exercise and adopt a systematic meal schedule, especially if you are a shift worker. Also, avoid caffeine, nicotine, alcohol, and unnecessary drugs. The most important aspect of maintaining a good lifestyle is managing exposure to light which is a powerful signal to reset the sleep-wake cycle. Artificial light at night may lower the melatonin levels causing difficulty in sleeping. Reducing the lights for a period before sleeping will help reduce the symptoms of circadian rhythm disorder. Light-blocking glasses help shift workers when they are outside during the daytime.
- Bright-Light Therapy:
People with sleep-wake cycle disorder respond well with timed exposure to bright light (greater than 2000 lux) to advance or delay sleep. It is even helpful for shift workers during their shift. In this approach, you need to sit in front of a lightbox every day. It helps adjust the amount of melatonin produced by your body to reset your rhythm.
If you suffer from a delayed sleep disorder, bright-light therapy is performed in the morning, and decreased light exposure in the evening may help. Also, reduce the use of computer and mobile screens at night. On the contrary, if you have an advanced sleep disorder, use the lightbox in the evening.
- Chronotherapy:
It is basically a behavioral treatment that includes the use of progressive advancement or delay of sleep time following a person's desired schedule. For example, in delayed sleep syndrome, a delay of 3 hours per day is advised with strict maintenance of a regular bedtime hour. It requires serious commitment to shift the cycle to get the desired sleep-wake schedule successfully.
- Medications:
Mainly the treatment focused on behavioral aspects. The choice of medication and supplements depends on the type and severity of the disorder:
- Melatonin receptor agonists are used to treat non-24-hour sleep disorders.
- Melatonin supplements are recommended in jet lag, delayed sleep-wake cycle, non-24-hour sleep-wake rhythm disorder, and sleep onset insomnia in the elderly. It enhances the natural sleep process by resetting the sleep-wake cycle. It is available as an over-the-counter drug, but the FDA hasn't approved them yet, so it isn't entirely clear how effective it is.
Other drugs used are:
- Beta-Blockers; decrease the levels of melatonin in your body during the daytime.
- Benzodiazepines are short-acting benzodiazepines such as Xanax, used early in combination with behavioral treatment. It is not used as a long-term treatment because of side effects like the risk of dependence.
- Non-benzodiazepine hypnotics are sleep medications like Suneta and Lunesta are gaining popularity because they don't have a significant effect on sleep architecture and are not connected with the rebound phenomenon in which the actual problem comes back at a higher level than before.
Conclusion:
Circadian rhythm disorders happen due to continuous disruption of one's sleep patterns. Whenever there is a misalignment of the timing of endogenous rhythm and external environment, there is a dysfunction in our internal clock. The primary agents of this system are melatonin and light. There are various types of the disorder we discussed above with their own features. One must not hesitate to contact a healthcare professional to discuss changes in the sleep patterns and question the said treatment.
References:
- https://my.clevelandclinic.org/health/diseases/12115-circadian-rhythm-disorders
- https://www.nhlbi.nih.gov/health-topics/circadian-rhythm-disorders#:~:text=Treatments%20for%20circadian%20rhythm%20disorders,bright%20light%20therapy%2C%20and%20melatonin.
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3020104/
- https://www.webmd.com/sleep-disorders/circadian-rhythm-disorder-tests
- https://www.sleepfoundation.org/circadian-rhythm-sleep-disorders
- https://www.emedicinehealth.com/sleeplessness_and_circadian_rhythm_disorder/article_em.htm#what_are_the_symptoms_of_biological_clock_sleep_disorders
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