HEALTH TIPS: CIRCADIAN RHYTHM (BIOLOGICAL CLOCK)

Dr. Tariq Jagnarine
Family Medicine, Endocrinology/Diabetes

Circadian rhythms are physical, mental, and behavioural changes that follow a 24-hour cycle. These natural processes respond primarily to light and dark, and affect most living things, including animals, plants, and microbes. The brain receives signals based on the environment, and activates certain hormones, alters our body’s temperature, and regulates our metabolism to keep us alert or draw us to sleep.
Some may experience disruptions to their circadian rhythm because of external factors or sleep disorders. Maintaining healthy habits can help us respond better to this natural rhythm of our body.
There are several components that make up the body’s circadian rhythm. It is one of four biological rhythms in the body.

* Cells in the body
First, cells in the brain respond to light and dark. The eyes capture such changes in the environment, and then send signals to different cells about when it’s time to be sleepy or awake. Those cells then send more signals to other parts of the brain that activate other functions that make us more tired or alert.

* Hormones play a role
Hormones like melatonin and cortisol may increase or decrease as part of the circadian rhythm. Melatonin is a hormone that makes us sleepy, and the body releases more of it at night and suppresses it during the day. Cortisol can make us more alert, and the body produces more of it in the morning.

* Other factors
Body temperature and metabolism are also part of the circadian rhythm. The temperature drops when we sleep, and rises during awake hours. Additionally, the metabolism works at different rates throughout the day.
Other factors may also influence the circadian rhythm. The rhythm may adjust based on the work hours, physical activity, and additional habits or lifestyle choices.

Age is another factor that influences the circadian rhythm. Infants, teens, and adults all experience circadian rhythms differently.

Circadian rhythm in babies
Newborns do not have a circadian rhythm developed until they are a few months old. This can cause their sleeping patterns to be erratic in the first days, weeks, and months of their lives. Their circadian rhythm develops as they adapt to the environment and experience changes to their bodies.
Babies begin to release melatonin when they are about three months old, and the hormone cortisol develops from 2 months to 9 months old. Toddlers and children have a fairly regulated sleep schedule once their circadian rhythm and corresponding body functions mature. Children need about 9 or 10 hours of sleep each night.

* Circadian rhythm in teens (sleeping late)
Teenagers experience a shift in their circadian rhythm known as sleep phase delay. Unlike in their childhood years, with early bedtimes around 8 or 9 pm, teenagers may not get tired until much later in the night.
Melatonin may not rise until closer to 10 or 11 pm, or even later. That shift also results in a teenager’s need to sleep later in the morning. Their peak sleepy hours at night are from 3am to 7am — or may even be later — but they still need the same amount of sleep as children.

* Circadian rhythm in adults
Adults should have a pretty consistent circadian rhythm if they practise healthy habits. Their bedtimes and wake times should remain stable if they follow a fairly regular schedule and aim for seven to nine hours of sleep every night. Adults likely get sleepy well before midnight, as melatonin is released into their bodies. They reach their most tired phases of the day from 2am to 4am, and from 1pm to 3pm.
Older adults may notice their circadian rhythm changes with age, and they begin to go to bed earlier than they used to, and wake in the wee hours of the morning. In general, this is a normal part of aging.

Causes of Disrupted Circadian Rhythm
Sometimes it is not possible to follow the circadian rhythm, and the lifestyle needs and internal clock clash. This can occur because of:
* Overnight or off-hours work shifts that go against the natural light and dark times of day.
* Work shifts with erratic hours.
* Travel that spans the course of one or more different time zones.
* A lifestyle that encourages late-night hours or early wake times.
* Medications’ use.
* Stress.
* Mental health conditions.
* Health conditions like brain damage (cancer, infection, and trauma), dementia, head injuries, or blindness.
* Poor sleep habits, including lacking a sleep schedule, eating, or drinking late at night, watching screens too close to bedtime, or not having a comfortable sleeping space.

SOLUTIONS
Disruptions to the circadian rhythm may be experienced, but the rhythm can get back on track if a healthy 24-hour schedule is promoted, such as:
* Trying to adhere to a routine each day.
* Spending time outdoors when it’s light outside, to boost the wakefulness.
* Getting enough daily exercise — twenty or more minutes of aerobic exercise is generally recommended.
* Sleeping in an environment that promotes rest, with proper lighting, a comfortable temperature, and a supportive mattress.
* Avoiding alcohol, caffeine, and nicotine in the evenings.
* Powering down the screens well before bedtime, and engaging in something analog, such as reading a book or meditating.
* Do not nap late in the afternoon or evening.

Effects on Health
Maintaining the circadian rhythm is vital to health. If we experience a disruption to the circadian rhythm and struggle to get the proper amount of sleep, we may experience both short-term and long-term consequences to our health.
Disruption to the circadian rhythm can cause health conditions in several parts of the body in the long term. Those include the organs, cardiovascular system, metabolism, gastrointestinal system, skin etc.
This can make persons more susceptible to diabetes, obesity, and mental health conditions as well.
Short-term disruptions to the circadian rhythm may result in problems with memory, or lack of energy. It may also take longer to heal an injury by not getting enough sleep.
Reach out to a doctor if experiencing prolonged difficulties sleeping, or extreme fatigue during the day, to find out how to realign with the circadian rhythm and get proper rest.