What Is Blue Light? How Does It Impact Sleep?

Updated Dec 14, 2024 | 10:45 PM IST

SummaryScreens of electronic devices such as smartphones, computers, tablets, and televisions emit blue light. But does it impact your natural sleep cycle and circadian rhythm?
Blue Light

Blue Light (Credit: Canva)

Blue light emitted by devices like smartphones, computers, and televisions is becoming a major factor disrupting our sleep cycles. Research reveals that a significant number of Americans use electronic devices close to bedtime, contributing to poor sleep quality. Reducing exposure to blue light, particularly in the evening, is a simple yet effective way to help your body prepare for restful sleep.

What Is Blue Light?

Blue light is part of the visible light spectrum and is emitted by natural and artificial sources like the sun, fluorescent lights, LED lights, and digital screens. This wavelength is known for influencing our alertness, mood, and sleep patterns. During the day, blue light plays a role in regulating circadian rhythms, helping us stay alert and focused. However, exposure to it in the evening can have a detrimental effect on sleep quality.

How Does Blue Light Impact Circadian Rhythms?

Circadian rhythms are 24-hour cycles that control essential bodily functions, including sleep. Light is the primary factor that aligns these rhythms with day and night. Historically, exposure to sunlight during the day helped set our body clocks, signaling when to be awake and when to sleep. However, the widespread use of artificial lighting and electronic devices has introduced more light exposure after dark, disrupting these natural cycles.

Blue light, in particular, has the strongest impact on circadian rhythms. During daylight hours, blue light helps us feel alert by stimulating the brain, raising body temperature, and increasing heart rate. But in the evening, exposure to blue light can confuse the body’s internal clock, suppressing melatonin—the hormone responsible for making us feel sleepy. As a result, our brains may remain in “daytime mode,” preventing us from winding down for the night.

Health Consequences Of Disrupted Sleep

Persistent disruption of circadian rhythms can lead to a range of health issues, including metabolic disorders, poor mental health, and increased risk for conditions like depression and anxiety. Furthermore, the inability to sleep well at night affects cognitive performance, mood, and overall well-being. Chronic exposure to blue light in the evening may significantly contribute to these negative health outcomes.

Devices That Emit Blue Light

Many common devices in our daily lives emit blue light, including:

- Smartphones and tablets

- Computer monitors and laptops

- Televisions and e-readers

- LED and fluorescent lighting

- Video game consoles

How To Minimize Blue Light Exposure

To reduce the effects of blue light on your sleep, here are some practical strategies:

1. Turn off screens before bed: Try to avoid using electronic devices at least two to three hours before bedtime. Reducing screen time helps prevent blue light from interfering with melatonin production.

2. Adjust your lighting: Dim your home’s lights or switch to warmer-toned lighting in the evening. You can also use lamps with red or orange light, which are less likely to impact your circadian rhythms.

3. Night mode settings: Many smartphones and computers have a "night mode" feature that reduces blue light emission. Make use of these features to limit exposure in the hours leading up to bedtime.

4. Blue light-blocking glasses: Special glasses designed to filter out blue light may be helpful for some individuals. These glasses can block or reduce the melatonin-suppressing effects of blue light.

5. Apps for blue light reduction: There are several smartphone and computer apps available that reduce blue light emission, allowing you to use your devices before bed without disturbing your sleep.

6. Create a sleep-friendly environment: If you can’t control light sources in your bedroom, consider using an eye mask to block out ambient light and promote better sleep.

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1 In 5 US Lung Cancer Patients Never Smoked: Report Highlights Hidden Risk Factors

Updated Oct 25, 2026 | 10:06 AM IST

SummaryA recent report highlighted an alarming number of lung cancer cases in the US among people who have never touched a cigarette.
1 In 5 US Lung Cancer Patients Never Smoked: Report Highlights Hidden Risk Factors

Credit: AI

One of the most common contributing factors in lung cancer is smoking but a recent report suggests an alarming pattern in which cases among non-smokers are on the rise.

Pope Leo XIV was recently diagnosed with lung adenocarcinoma, a type of aggressive cancer that develops in the cells lining the lungs. He had no history of smoking. The 71-year-old pontiff underwent surgery to have part of his right lung lobe removed. According to reports, he is out of the hospital and recovering well.

Another case is of Stanford physician Bryant Lin whose stubborn cough led him to seek medical attention. After six weeks, he underwent an X-ray. The diagnosis stated that he had stage 4 lung cancer. Lin was less than a month away from turning 50, and he had never smoked a cigarette in his entire life.

“Definitely a shock,” Lin recalled according to The Washington Post. By the time doctors identified the cancer in spring 2024, it had spread to his liver, bones and brain.

According to the US Centers for Disease Control and Prevention (CDC), around 10% to 20% of lung cancers in the United States are reported in people who have never smoked or have smoked fewer than 100 cigarettes in their lifetime. That amounts to an estimated 20,000 to 40,000 cases annually.

For these patients, their no-smoking history can delay diagnosis and treatment. Hence, researchers are now looking into how environmental exposures, genetic causes and the biology of tumours may contribute to lung cancer in non-smokers.

Lung Cancer In People Who Have Never Smoked

Also read: Pope Leo XIV, Diagnosed With Lung Cancer, Undergoes Surgery As His Brother Battles Relapsed Multiple Myeloma

Smoking remains the leading risk factor for lung cancer. But other reasons like exposure to radon, secondhand smoke, air pollution and asbestos can also increase risk. Family history plays a role, especially when a first-degree relative has cancer before age 50.

Researchers are also examining genetic differences that may help explain why some people develop lung cancer despite never smoking.

A study published in September identified a rare genetic mutation concentrated in the southeastern United States that was associated with a 60-fold higher risk of lung cancer among non-smokers. The finding focuses on a possible role for inherited susceptibility, but it does not explain most cases in this group.

Lung cancer also has a different demographic profile among people who have never smoked. Women who have never smoked are more than twice as likely as their male counterparts to develop lung cancer.

“Two-thirds of nonsmoking-related lung cancer happens in women, so there’s certainly an association with female sex,” said Jaclyn LoPiccolo, a medical oncologist at Dana-Farber Cancer Institute who co-authored the mutation study.

She added, “Nonsmoking-related lung cancer is also more common in people of East Asian descent, but whether that’s a genetic or environmental association, we don’t yet know.”

These Cancers Are Often Diagnosed Late

Also read: Pope Leo XIV Resumes Daily Activities After Lung Cancer Surgery: How Recovery Looks Like After Lung Lobe Removal

People who have never smoked may not recognise a persistent cough or other respiratory symptoms as signs of lung cancer. Doctors may initially consider more common explanations if the patient has no smoking history.

Never-smokers are often diagnosed late at more advanced stages of the disease because their doctors initially consider lung cancer to be less likely.

Haiying Cheng, a medical oncologist at Montefiore Einstein Medical Center in New York, said the stigma surrounding the disease can compound the problem. “A cancer diagnosis should never become a judgment about a patient,” Cheng said.

She added that clinicians need to consider assumptions beyond smoking when it comes to lung cancer and focus on the patient’s risk profile and tumour biology.

Lin is receiving antibody therapy targeting a cancer-driving mutation. He had a positive response to treatment.

“The treatment has done wonders for me,” he said. “When I was a medical student or resident, I would have never thought a Stage 4 lung cancer patient could be very productive and have a high quality of life almost two-and-a-half years after diagnosis.”

In the United States, the US Preventive Services Task Force recommends annual low-dose CT screening for adults aged 50 to 80 who have a smoking history. People who have never smoked are not included in these recommendations.

As researchers dig deeper into lung cancer chances in non-smokers, there is growing interest in different screening recommendations. Taiwan, for example, has a national early-detection programme offering low-dose CT scans to non-smokers with a family history of lung cancer.

Lin has urged his own sons to consider screening at a younger age. “I’ve got two sons, and I told them, ‘When you hit 45 or even 40, think about getting screened,’” he said.

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Women And Arthritis: Why Risk Increases After 40

Updated Oct 25, 2026 | 01:00 PM IST

SummaryDiscover why arthritis risk rises in women after 40, how hormonal changes affect joints, warning signs to watch for, and expert-backed ways to protect joint health.
Women And Arthritis: Why Risk Increases After 40

Credit: AI Generated

Many women in their forties come to my clinic with joint pain they have lived with for months, assuming it is part of getting older. World Arthritis Day is a good time to look at what changes in a woman's joints after 40 and why it pays to act early.

Why Does The Risk Rise After 40?

The biggest shift is hormonal. Oestrogen helps regulate inflammation and protects cartilage, bone and muscle. As levels fluctuate during perimenopause and fall after menopause, the joints lose part of that protection. A 2024 review in the journal Climacteric named this pattern the musculoskeletal syndrome of menopause, estimating that more than 70% of women experience joint or muscle symptoms during the transition and about one in four find them disabling.

Lower oestrogen also speeds up the loss of muscle and bone. When the thigh muscles weaken, the knee absorbs more shock with every step, which is one reason knee osteoarthritis becomes more common in women at this stage. Osteoarthritis, the gradual wear of the cartilage cushioning the bones, commonly affects the knees, hips, hands and spine. Old injuries, excess weight, and family history increase the risk.

Women are also two to three times more likely than men to develop rheumatoid arthritis, an autoimmune condition in which the immune system attacks the joint lining. It most often begins between the ages of 30 and 60.

Which Signs Should You Watch For?

One simple check is how long your joints stay stiff in the morning. Stiffness and pain that increases with movement is typical of osteoarthritis. Stiffness even with rest, especially with swelling in the small joints of both hands or wrists, suggests inflammatory arthritis and needs prompt assessment. Other signs include pain while climbing stairs or getting up from the floor, a grating feeling in the knee, firm bony swellings on the finger joints and tiredness out of proportion to your activity.

Not every ache after 40 is arthritis. Menopause-related pain, for instance, tends to move around the body. An examination, an X-ray, and simple blood tests can tell these conditions apart, so avoid self-diagnosis.

How Can You Protect Your Joints?

  • Strength training: Muscle-strengthening exercise at least twice a week, focused on the thighs and hips, takes load off the knees.
  • Low-impact activity: Walking, swimming, and cycling keep joints mobile without straining them.
  • Weight: A study of adults with knee osteoarthritis found that every kilogram lost takes about four kilograms of load off the knee with each step.
  • Diet: Get enough protein and calcium, and ask your doctor whether you need a vitamin D test.
  • Daily habits: If your knees already hurt, limit deep squatting and long hours sitting cross-legged on the floor, wear supportive footwear, and avoid smoking.

When Should You See A Doctor?

Consult an orthopaedic specialist if joint pain or stiffness lasts beyond a few weeks or affects daily tasks. In rheumatoid arthritis, early treatment can slow the disease and prevent permanent joint damage. A suddenly hot, red, swollen joint with fever needs same-day attention, as it may signal infection.

Arthritis does not have to come with turning 40. Women who notice the early signs, keep their muscles strong, and see a doctor in time can stay active and independent well into later life.

By Dr Saurabh Bansal, Consultant Orthopaedic Surgeon, PB Health

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Can Holding Your Urine During Long Office Hours or Traffic Jams Affect Urinary Health?

Updated Oct 24, 2026 | 11:00 PM IST

SummaryOccasionally holding urine during long meetings or traffic jams is generally harmless for healthy adults. However, repeatedly delaying urination may cause discomfort and aggravate existing bladder problems. Learn how this habit can affect urinary health and when to seek medical advice.
Can Holding Your Urine During Long Office Hours or Traffic Jams Affect Urinary Health?

Credit: iStock

Holding urine occasionally, such as during a long meeting or traffic jam, is generally not harmful for most healthy adults. However, repeatedly delaying urination for extended periods may affect urinary health, particularly in people who are prone to urinary tract infections (UTIs) or have existing bladder problems.

What Happens When You Hold Urine for Too Long?

When urine remains in the bladder for too long, it can become uncomfortable and may contribute to bladder overdistension. In some individuals, particularly those with underlying urinary retention or bladder dysfunction, regularly postponing urination may worsen existing problems.

While holding urine does not directly cause a UTI in every case, incomplete bladder emptying can increase the risk of infection.

Also read: Are People With CKD At Higher Risk Of Dementia And Cognitive Problems?

Why You Should Not Reduce Water Intake to Avoid Bathroom Break

People who work long hours or commute frequently should try to respond to the urge to urinate rather than routinely suppressing it.

Maintaining adequate hydration is equally important, as deliberately drinking less water to avoid bathroom breaks can lead to concentrated urine and may increase the risk of certain urinary problems like concentrated urine leading to crystallization and stone formation.

When Should You Seek Medical Advice?

If you experience persistent urgency, burning during urination, lower abdominal discomfort, difficulty passing urine or blood in the urine, seek medical advice. Developing regular bathroom habits and ensuring convenient access to washrooms can help support long-term urinary health.

It is also important to recognise when urinary symptoms may indicate a more serious problem. Inability to pass urine despite a strong urge, particularly when accompanied by severe lower abdominal pain or swelling, requires urgent medical attention.

Fever, chills or pain in the back or side alongside urinary symptoms may indicate a kidney infection and should be assessed promptly. Avoid assuming that such symptoms are simply the result of holding urine for too long.

By Dr. Vikram Kalra, Principal Director - Nephrology and Kidney Transplant, Aakash Healthcare Multi Speciality Hospital, Dwarka

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