Is there a connection between the body clock and cancer?
Most of us recently experienced our second time change of the year, when we “fell back” an hour to allow standard time to resume.
This change marked the end of daylight saving time, which won’t start again until March next year.
The fall time change is usually a little more welcome than the spring time because we all get an extra hour of sleep. But if you’re not feeling particularly rested, or perhaps you’re feeling more tired than usual, don’t worry. You are not alone.
Every time you go through these time changes, you disrupt your normal biological clock. And if you do that too often, scientists say it can increase your risk of certain types of cancer.
The good news is that the opposite – working with your natural body clock – can help reduce your risk of cancer. In this post, we’ll explore both sides of this issue and show you how you can benefit from the research to stay as healthy as possible.
Body clock and cancer: what is the body clock?
Also called the “circadian rhythm” or “biological clock,” the body clock refers to the internal cycles your body goes through in a 24-hour period. They are the natural physical, mental and behavioral changes that occur every day, usually in response to daylight and night.
Your biological clock is composed of specific molecules (proteins) that interact with cells throughout the body. You have a general master clock, but each organ and group of tissues also has its own clocks.
Every morning, your eyes absorb sunlight, which sends signals to your brain. These signals help your body wake up and get started with the day. During the day, the master clock in the brain sends signals to the rest of the brain and body to keep you awake and maintain your energy.
At night, when daylight naturally fades, it triggers the release of hormones that cause you to slow down, feel drowsy, and eventually fall asleep.
Your internal body clock ensures that many of your bodily functions run on a schedule. That’s why you tend to feel hungry at certain times, why you prefer exercise at certain times over others, and why you get tired at certain times.
What determines the schedule of the body clock?
Each of us is born with our own unique body clock. Our genes influence the settings of that clock, including when we feel the most energy when we naturally go to sleep and wake up, what our normal blood pressure is, and even our typical mood.
If we left it to ourselves—without anything else determining our schedules—we would likely follow this internal clock every day, allowing it to determine when we go to sleep and wake up, when we eat, and when we exercise.
This is why some people are what we call ‘night owls’ – they have a later biological clock – while others are ‘morning larks’. Some people land right in the middle. You probably know what you naturally gravitate towards when it comes to the times when you’re likely to feel more energetic or sleepier.
However, the environment around us can also have a major impact on the body clock. For example, if your job requires you to work shifts, you need to disrupt your normal body clock to work during the times you normally sleep, and then go to sleep during the day.
These types of disruptions can negatively impact our health over time.
Age can also influence our circadian rhythms. While teens may need a later wake-up time, older adults often have a harder time falling asleep and waking up earlier in the morning.
Body clock and cancer: what influence does the body clock have on health?
Our master clock influences important functions in our body, including hormone release, eating habits, digestion, sleep, metabolism and body temperature. It affects the strength of our immune system, appetite and mood. Scientists have discovered that our circadian rhythms also influence mental health.
We know this because we have seen the effects of disrupting the biological clock. You already know that if your normal sleep schedule is disrupted throughout the week, you will not only feel tired and irritable, but you will also likely eat more than usual, gain weight, and lose energy.
If you’ve ever worked a shift, you also know how your body can struggle to recover from the disruption. Your brain doesn’t get the amount of light it needs when you wake up, which throws your hormones out of whack and makes you feel like you’re experiencing jet lag.
Today’s “always-on” society can also have a major impact on our circadian rhythms and our health. Working too late under artificial light can confuse your brain about when it is daylight and when it is night. Exposure to light at late hours can cause your brain to release ‘wake hormones’, making it harder for you to fall asleep, leaving you drowsy the next day.
Your eating habits can also influence your internal body clock. Eating too late (dinner late or a late-night snack) triggers your digestive system when it’s used to slowing down. That can keep you awake and affect your sleep. The next day you will be tired and sluggish and may be carrying more weight.
Body clock and cancer: how they are related
Scientists already know that long-term shifts to the internal body clock can increase the risk of cancer. That’s because their studies among shift workers show that they are at greater risk of the disease.
A recent report from the National Toxicology Program (NTP) showed a persistent link between shift work and cancer risk. “In the NTP report,” the Centers for Disease Control and Prevention (CDC) stated: “It was concluded that there is ‘high certainty’ that persistent night work resulting in disruption of the biological clock can cause cancer in humans.”
The International Agency for Research on Cancer (IARC) has gone so far as to conclude that night work is ‘probably carcinogenic to humans’, based on evidence from human studies of breast and prostate cancer and research into the mechanisms of how cancer develops .
One of the problems is that disruption of the body clock can damage the systems we have in our bodies that help prevent cancer. For example, melatonin – the sleep hormone – not only helps us fall asleep, but also helps stop tumor growth and protect us from the spread of cancer cells.
When we disrupt our normal sleep rhythm by working late at night or exposing ourselves to light (including computer, tablet and phone lights) late at night, we reduce the release of melatonin.
That not only makes it harder to fall asleep, but also robs the body of the protective effects of melatonin.
There are also other mechanisms that increase the risk of cancer. Circadian disruption affects the chemical reactions that produce energy in the body. It messes with the immune system and compromises DNA repair in cells.
And it’s not just cancer we have to worry about. Regular disruption of the body clock has also been linked to the following health problems:
Body Clock and Cancer: What You Can Do
New research shows that targeting the body’s biological clock can help treat cancer. According to a 2018 studyTwo compounds that target components of the circadian clock killed several types of cancer cells and slowed the growth of brain tumors.
Research has also shown this certain chemotherapy treatments are more effective when given in accordance with the patient’s natural body clock rhythm.
In the meantime, what we all want to do is prevent cancer from developing in the first place. Follow these tips to keep your body clock on track and reduce your risk of disease:
- Maintain a consistent sleep schedule: Go to bed and get up at the same time every day, even on weekends.
- Avoid exposure to light at night. At least an hour before bedtime, turn off the lights and technological gadgets, including your phone, computer, and television. Do something calm and relaxing, such as taking a warm bath, reading, or listening to soothing music.
- Go outside in the morning. Exposing yourself to bright light in the morning is key to getting your normal circadian rhythm going. Natural sunlight is ideal. On cloudy days, try a sunlamp. Place your workplace near a window if possible.
- Avoid eating late in the evening. Stop eating at least two hours before bedtime. When you get hungry, try drinking a large glass of water or a hot cup of tea.
- Practice regularly. Daily exercise can keep all your body systems on track. It can also help prevent cancer on its own.
- Watch your caffeine intake. Individuals differ in their ability to metabolize caffeine. If you have trouble sleeping, avoid caffeine after noon.
- Create a comfortable sleeping atmosphere. This means a dark, cool room and a comfortable mattress.
Do you have trouble maintaining your normal body clock?
