Know how?
Although we won’t hear it tick, our body has its own clock. The physical and mental changes it causes are called circadian rhythms. Circadian rhythms affect our sleep patterns as well as other ways our body works, like our hormones, body temperature, and eating habits. When they get out of sync, they might also cause problems with our health. They’ve been linked to different disorders including diabetes, obesity, depression and cancer.
How does the Sleep-Wake cycle work?
About 20,000 nerve cells make up our “master clock,” a part of our brain called the suprachiasmatic nucleus. This structure controls the Sleep-Wake cycle. While largely guided by your genes and other natural factors inside one’s body, things in the outside world can also alter them.
The biggest cue is light which is linked to the sleep-wake cycle. Our bodies are wired to sleep when it’s dark and stay awake when it’s light outside. Nerves directly link eyes and body’s master clock. When daylight fades, eyes signal your brain to make more melatonin, a hormone that makes us feel sleepy. And when the sun rises again, the signals tell the brain to turn down the melatonin.
Different People have Different Patterns
How we feel in respect to our energies during certain part of the day is also set in a pattern which is associated with our “chronotype” or in simpler words our personal circadian rhythm. This pattern varies from person to person, although they tend to run in families.
A person can fall in one of the following groups:
Early birds: Those who find it easy to wake up in the morning and have the most energy early in the day. Simply put a morning persons!
Night owls: An evening person! One who finds it hard to wake up in the mornings and feel alert. They are most energetic much later in the day, like 11 p.m.
However, your chronotype isn’t set in stone, though. Circadian rhythms naturally change as you age and also get adjusted as per your daily habitual schedules.
How it gets out of sync?
- 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 you take.
- Stress.
- Mental health conditions.
- Health conditions like brain damage, 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.
- Many women notice that they sleep worse before their period starts. This may be due, at least in part, to a change in circadian rhythms.
What’s the link with cancer?
- Considering the results of several population and laboratory-based studies, the World Health Organization has designated circadian disruption as a likely carcinogen.
- International Agency for Research on Cancer (IARC) has also classified “shift-work that involves circadian disruption” as potentially “carcinogenic to humans (Group 2A)” in 2007 and again in 2019.
- Several epidemiologic studies too have reiterated the fact that sleep-wake cycle disruptions are associated with increased risk of cancers of the prostate, breast, colon, liver, pancreas, ovary, and lung.
- Loss of circadian control also affects the efficacy of anticancer treatment and might lead to early mortality amongst patients with cancer.
- If you have a family history of cancer, then the disrupted lifestyle pattern such as night shift work increases your risk. Try to adhere to a routine each day to reduce your risk.
- Disrupted cycle can also increase the risk of recurrence among cancer patients.
- Studies have suggested that certain anti-cancer drugs when given at a specific time, have shown better efficacy in treatment.
What can you do to keep your circadian clock in sync?
- Set a schedule / pattern and work accordingly.
- Spend time outdoors when it’s light outside to boost your wakefulness.
- Get enough daily exercise — twenty or more minutes of aerobic exercise is generally recommended.
- Sleep in an environment that promotes rest with proper lighting, a comfortable temperature, and a supportive mattress.
- Avoid alcohol, caffeine, and nicotine in the evenings.
- Power down your screens well before bedtime and try engaging in reading a book or meditating.
- Do not nap late in the afternoon or evening.
Living a healthy, active lifestyle that promotes proper rest will help you maintain this important component of your body and lower your risk of lifestyle related diseases including cancer.
Know the Writer:Dr (Prof) Meenu Walia is a renowned Medical Oncologist (Cancer Specialist) with almost 30 years of medical experience. She is India’s first DNB, Medical Oncologist and has several laurels attached to her name such as the “Bharat Jyoti Award”, “Inspiring Healthcare Leaders—Dronacharya Award” and “Most Influential Women of 2021 award” to name a few. A keen cancer researcher, she is the Principal Investigator of several global clinical trials. Beyond medicine, she is deeply passionate about the welfare of cancer patients and is thus actively involved with several NGOs and awareness activities. She is a charismatic speaker having delivered an inspiring and popular talk on TEDx platform as well as authored a book for cancer patients and caregivers, “Tips for Happiness in The Shadow of Cancer”.