Oncologists Say This Is the #1 Cancer Risk Factor No One Talks About
We have good news and bad news. The good news is that cancer deaths are on the decline in the U.S. Increased awareness, screening and personalized care based on risk factors have played a big role in this welcome development. The bad news? Rates for some cancer diagnoses are increasing in younger populations under 50, like colon cancer.
"Overall, these patterns highlight an important shift: while progress has been made in reducing mortality, cancer is increasingly being diagnosed earlier in life, reinforcing the importance of prevention, awareness and timely screening," says Dr. Brian Helfand, MD, Ph.D., a urologic oncologist at Endeavor Health.
A cancer diagnosis can feel cruel and even random, especially (but of course not only) in younger people. Sometimes, we can't control our cancer risk, such as with genetics, but other factors are changeable. For this reason, Dr. Helfand says understanding risk factors is crucial to getting ahead of cancer-and putting yourself in the best position to beat it and even lower your odds of developing it.
"Rather than thinking of cancer as something random, understanding risk factors helps to see it as the result of many influences adding up, including lifestyle, environment and biology," he tells Parade. "When a person understands their risks, they can take practical steps to lower them, such as adjusting daily habits or staying on top of recommended screenings."
Dr. Helfand adds that it can help you tune into your body sooner and seek care earlier, which is when treatment is often more effective. Speaking of daily habits, one is often overlooked as something that can increase or decrease cancer odds. Below, oncologists share their choice for the #1 cancer risk factor that no one talks about-and what to do about it.
Oncologists Say This Is #1 Cancer Risk Factor No One Talks About
"It has become increasingly recognized that sleep quality influences cancer risk," Dr. Helfand says.
Another oncologist echoes these sentiments. "In a very basic sense, cancer is a result of the body's inability to eliminate mistakes that occur during natural cell growth," explains Dr. Kathryn M. Eckert, DO, a breast surgical oncologist for Hackensack Meridian Jersey Shore University Medical Center.
Dr. Eckert shares that the theory is that, when sleep is poor, your body's natural repair strategies are affected, and your cancer risk goes up. But she concedes it's hard to create and complete studies on the theory, so there's limited data on it right now.
Still, we do have some data. For instance, a 2023 study of more than 78,000 people published in Public Health suggested a link between poor overall quality scores, including for people with insomnia and who snore, and an increased risk of overall and site-specific cancers, such as breast and kidney cancer. The American Cancer Society says more research is needed, but also points to research indicating that poor sleep can contribute to a person's cancer odds.
4 Reason Why Poor Sleep Can Increase Your Cancer Risk
We hate to give you another reason to toss and turn, but oncologists warn that not getting enough sleep can raise cancer risks. Understanding why is one step toward action.
1. It can affect your hormones
Lack of sleep disrupts your natural hormone cycles. "Everyone's internal clock depends on consistent sleep to regulate hormones like melatonin, which not only helps people fall asleep but also plays a role in controlling how cells grow and repair," Dr. Helfand says.
That's an issue because the body needs to get to sleep so it can naturally repair cells.
Plus, melatonin doesn't just help you get to sleep-research suggests it has anticancer effects, too. "Sleep disruption may decrease or block melatonin release and prevent its antitumor actions," says Dr. Alison Stopeck, MD, the associate director of clinical and translational research at the Stony Brook Cancer Center.
Melatonin isn't the only hormone affected by sleep. "Sleep is important for decreasing stress and stress hormones, regulating the repair of DNA that occurs naturally in people, and generally promotes a healthy lifestyle, including maintaining ideal body weight," Dr. Stopeck adds.
Chronic psychological stress is another potential cancer risk factor.
2. Poor sleep can affect your immune system
We often think of the immune system as something that protects us from colds, but we also need to keep it strong to help us ward off chronic diseases, like cancer. Poor sleep can weaken the immune system.
"During restful sleep, the body works behind the scenes to identify and remove damaged or abnormal cells," Dr. Helfand explains. "Without enough quality sleep, this process becomes less effective, so harmful cells may linger longer than they should and can turn into cancer cells."
3. It can trigger chronic inflammation
Our bodies need some inflammation to heal, but too much of it can, over time, increase cancer odds.
"Chronic poor sleep increases inflammation in the body," Dr. Helfand notes. "While inflammation is useful in short bursts, like when a person is healing from an injury, long-term inflammation can damage healthy tissues and create conditions that make it easier for cancer to develop."
4. Sleep deprivation can lead to other poor lifestyle choices
It's hard to cook for yourself, and it's easy to grab ultraprocessed convenience-store options when you're exhausted. Exercising after hitting "snooze" 12 times? Not likely. Yet, diet and exercise are critical components of cancer prevention.
"As a result, prioritizing high-quality sleep can help people make better dietary decisions, thereby improving body weight and decreasing cancer risk," Dr. Eckert says. "Regular exercise has been independently linked to cancer risk reduction for several cancers, but may also influence cancer risk by improving body weight."
Related: Oncologists Say This Popular Air Fryer Mistake Could Increase Cancer Risk
How To Get Better Sleep
Getting better sleep can feel like a steep hill to climb. However, oncologists share that tweaking one habit at a time can make a big difference. Here are their top tips for getting better sleep-and lowering your cancer risk while you're at it.
1. Skip the nightcap
Alcohol helps you fall asleep fast, but the sedative effect is misleading. Dr. Eckert points out that alcohol can decrease the amount of time you spend in the all-important restorative sleep.
"Limiting alcohol consumption can increase the amount of restful sleep and allow you to wake feeling more well-rested," she says.
Related: This 3-Minute Habit Could Help You Sleep Through the Night
2. Stick to a schedule
There's room for spontaneity in life, but oncologists don't recommend surprising your body with a new bedtime each night.
"Keeping a consistent sleep schedule is one of the most effective ways to improve sleep quality," Dr. Helfand says. "Going to bed and waking up at the same time each day helps regulate your internal clock, making it easier for your body to know when it's time to wind down and when it's time to wake up."
3. Limit screens before bed
Whether you're doom-scrolling or comfort-watching sourdough-baking sessions, screens before bed can wreak havoc on sleep.
"Limiting screen time before bed is also important because the blue light emitted from phones, tablets and TVs can suppress melatonin production," Dr. Helfand says. "This can trick your brain into thinking it's still daytime, delaying the natural process of falling asleep."
Related: Want To Sleep Better? This Is the Best Time of Day To Take Magnesium, Experts Say
4. Create a sleep den
Dr. Helfand reports that cool, dark and quiet sleep spaces promote more restorative rest.
"Darkness signals your body to produce melatonin, cooler temperatures help initiate sleep and a quiet setting reduces interruptions that can pull you out of important sleep stages," he explains. "Together, these habits help the body carry out the overnight repair work that supports long-term health."
5. Get tested for sleep disorders
If none of the above are working or if someone has told you that you snore, Dr. Helfand suggests getting tested for sleep disorders. He says that certain medical conditions, like obstructive sleep apnea and restless leg syndrome, can disrupt restorative sleep.
"Effective treatments are available and can improve both sleep quality and overall health," he emphasizes.
Related: Is 7 Hours of Sleep Enough? Experts Share the Truth
Other Cancer Risk Factors To Know About
Not getting enough sleep may increase cancer risk, but it's not the only thing to be mindful of. "Many cancer risk factors are within a person's control, and these are often the most impactful over time," Dr. Helfand says. "Making gradual, consistent improvements in these areas can meaningfully reduce risk."
He reports that modifiable cancer risk factors include:
- Tobacco use
- Alcohol intake
- Diet quality
- Physical activity
- Body weight
- Sun exposure
- Sleep habits
Related: Oncologists Are Begging You To Stop Making This Microwave Mistake Immediately
Dr. Helfand also notes that some factors are out of our hands, including:
- Age
- Genetics
- Family history
- Certain past environmental exposures.
"While you can't change these, knowing about them is still powerful as it allows you and your care team to personalize the patient's screening plan and stay vigilant for early signs of disease," he shares.
Up Next:
Related: ‘I'm a Gastroenterologist-Here's What I Eat To Help Prevent Colon Cancer'
Sources:
- Dr. Brian Helfand, MD, Ph.D., a urologic oncologist at Endeavor Health
- Annual Report to the Nation on the Status of Cancer. National Cancer Institute Surveillance, Epidemiology, and End Results Program.
- Colorectal cancer statistics, 2026. CA: A Cancer Journal for Clinicians.
- Self-reported sleep disorders and the risk of all cancer types: evidence from the Kailuan Cohort study. Public Health.
- Does Sleep Affect Cancer Risk? American Cancer Society.
- Dr. Kathryn M. Eckert, DO, a breast surgical oncologist for Hackensack Meridian Jersey Shore University Medical Center
- Dr. Alison Stopeck, MD, the associate director of clinical and translational research at the Stony Brook Cancer Center
- Melatonin suppresses PD-L1 expression and exerts antitumor activity in hepatocellular carcinoma. Nature.
- Psychological stress and cancer: new evidence of an increasingly strong link. Translational Medicine@UniSa.
- ACS Annual Statistics Report: Milestone 70 Percent 5-Year Survival Rate for all Cancers Combined; Largest Gains for Advanced and Fatal Cancers. American Cancer Society.
- Amount and intensity of daily total physical activity, step count and risk of incident cancer in the UK Biobank. British Journal of Sports Medicine.
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This story was originally published May 2, 2026 at 11:25 AM.