Sleep and the circadian rhythm

Circadian rhythms are 24-hour cycles in one's physical, mental, and behavioural states. Most living things, including animals, plants, and microbes, are impacted by these natural processes, which primarily react to light and darkness. Our daily sleep and wakefulness schedules are more easily managed thanks to it. Our environment sends signals to our brain, which then activates certain hormones, modifies our body temperature, and controls our metabolism to keep us awake or put us to sleep1.

They have an impact on a variety of functions, including hormones, body temperature, hunger and digestion, sleep-wake cycles, and more. When people discuss their circadian rhythms, they typically refer to their sleep patterns and any disruptions to their ability to rest and recover. But in turn, this has a significant effect on their level of vigilance and energy throughout the day2.

We must comprehend the rhythm of our 24-hour cycle in order to comprehend our own rhythm. Understanding our circadian clock will help us make the most of each day, whether it be by improving our ability to concentrate at work, feeling great after a run, or knowing when to unwind3.

Some people may experience circadian rhythm disturbances as a result of environmental factors or sleep problems. We can better respond to our body's natural rhythm by upholding healthy habits.

What influences Circadian Rhythms:

A biological clock that controls the body's daily cycle of circadian rhythms can be found in almost every tissue and organ. These clocks are actually protein-based molecules that can communicate with the cells in our body. All of these biological clocks are synchronized by a master circadian clock in the brain. The 20,000 nerve cells that make up the suprachiasmatic nucleus (SCN), the brain's control centre, are located in the hypothalamus. The eyes communicate information about the light in the environment to the SCN directly through the optic nerve. The SCN uses this information to produce melatonin, a hormone that induces sleep. Therefore, the SCN instructs the brain to produce more melatonin to make us drowsy when it is nighttime or when we are in a dark environment3.

A Description Of The Circadian Cycle4:

  • Lowest energy between 3 and 7 a.m.
  • As our body gets ready to wake up, our blood pressure spikes the most at 6:45 am.
  • The melatonin secretion halts at 7:30 am.
  • Bowel motions at 8:30 a.m.
  • Between 10 a.m. to 1 p.m. is peak alertness and energy.
  • The afternoon slump occurs between 1-3 pm.
  • Best work coordination at 2:30 pm.
  • The fastest reaction time is at 3:30 pm.
  • Best cardiovascular/muscular performance at 5 p.m.
  • Melatonin secretion begins at 9 pm.
  • Suppressed bowel movements at 10:30 pm.

Influence of Circadian Rhythms5,6:

Our circadian rhythm may occasionally change as a symptom of a more severe illness, circadian sleep cycle etc. The advanced sleep phase and the delayed sleep phase are two of these disorders. If a person has low vision, works irregular shifts, are a teenager or an older adult, they might be more vulnerable to these. When a person goes to bed and wakes up two hours or later than most people, they have a delayed sleep phase disorder. Young adults and teenagers are more likely to develop this condition. When compared to delayed sleep phase disorder, advanced sleep phase disorder is the opposite. In reality, a person goes to bed earlier than most people do, and they wake up very early in the morning.

Circadian rhythm disorders may make it difficult for us to fall asleep at night, keep us awake throughout the night, and prevent us from falling back asleep when we wake up in the middle of the night. These conditions' associated symptoms include insomnia, loss of sleep, fatigue throughout the day, and anxiety or depression. Our circadian rhythm is also affected by the following conditions such as jet lag from crossing several time zones quickly, shift work, and off-hours employment. Unable to establish a consistent schedule for sleep and wakefulness leads to irregular sleep-wake disorder.

How are sleep disorders of the circadian rhythm treated?6:

Treatment options for circadian rhythm sleep disorders vary based on the type of disorder and the degree to which it affects a person’s quality of life. Our healthcare provider will develop a personalized treatment plan, which improves the chance of success. Most treatment plans require a combination of approaches. Treatment options include:

Lifestyle and behaviour therapy: This approach encourages changes to improve sleep and develop good sleep habits. Good sleep habits include maintaining regular sleep-wake times (even on weekends and vacations); avoiding naps (exception: shift workers); developing a regular routine of exercise (avoid high-intensity exercise within one hour of bedtime); and avoiding alcohol, caffeine, and nicotine, and stimulating activities within several hours of bedtime.

Bright light therapy: This therapy is used to increase or delay sleep. This treatment's timing is very important, and a sleep expert's advice is needed. The mechanism by which bright light therapy functions is to reset the circadian clock so that it is more in tune with the cycle of daylight and darkness. A high-intensity light (2,000 to 9,500 lux) is required, and the duration and timing of exposure vary from one to two hours. Exposure to bright light in the morning may help if a person has a delayed sleep disorder. In addition, they should reduce the amount of light coming into their homes at night by turning off unnecessary lights and staying away from bright electronic devices. Exposure to bright light in the evening may help if they have an advanced sleep disorder.

Medications: Medications such as melatonin (available over the counter), wake-promoting agents (such as modafinil) or caffeine, and short-term sleep aids may be used to adjust and maintain the sleep-wake cycle to the desired schedule. Tasimelteon is approved to treat the non-24-hour sleep-wake disorder.

Chronotherapy: Depending on the type and severity of the disorder, this therapy strategy includes a gradual increase in sleep duration or a gradual decrease in sleep duration. This type of therapy requires a firm commitment by the patient and their partner, as it can take weeks to successfully shift the sleep-wake cycle. Once the desired schedule is achieved, they have to keep this regular sleep-wake schedule.

Referenc :

  1. Circadian Rhythm: What It Is, How it Works, and More. Learn more.
  2. Circadian Rhythms. National Institute of General Medical Sciences (NIGMS) Learn more.
  3. Griffiths, B. What is Your Circadian Rhythm and How Does It Affect Your Sleep? Polar Blog Learn more (2022).
  4. Mahaffey, K. Circadian Rhythms Explained from a Wellness & Fitness Perspective. Learn more.
  5. What Is A Circadian Rhythm And How To Reset Your Body Clock? Atlas Biomed blog | Take control of your health with no-nonsense news on lifestyle, gut microbes and genetics Learn more (2021).
  6. Circadian Rhythm Sleep Disorders: Types, Symptoms and Management. Cleveland Clinic Learn more.