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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Taking COVID And Flu Vaccines Together? Doctors Recommend Which Arm To Use

Updated Nov 21, 2025 | 09:00 PM IST

SummaryGetting COVID and flu vaccines at the same time? Learn which arm to use, how it affects immunity, and what side effects to expect.
arm to use for covid flu shot

Credits: Canva

COVID-19 and influenza are major causes of illness and death worldwide, particularly in countries like the US and UK. Vaccines can prevent infection or reduce the severity of illness, yet many people struggle to stay up to date due to time constraints or lack of motivation. If you are eligible for both vaccines around the same time, combining them in a single visit can save time and effort.

Doctors suggest that receiving both vaccines at the same visit can be a convenient approach, but a common question arises: which arm should you use? Is it safe to administer both vaccines in the same arm, or is it better to use separate arms?

One Arm or Two: Which One To Use For Both Shots?

Getting both shots in one visit sounds efficient, but you still need to decide whether to use one arm or two. Often, it comes down to personal preference, although sometimes the healthcare provider will make the decision. Is there evidence to guide this choice? Should both vaccines go in the same arm or one in each?

Which Arm Works Best for COVID and Flu Vaccines?

Animal studies suggest that administering the COVID and flu vaccines in the same limb may enhance immune responses. The mRNA COVID vaccines include a built-in immune booster called an ionizable lipid, which is a fatty molecule that protects the mRNA inside the vaccine.

Flu vaccines usually lack an adjuvant, but the built-in adjuvant in the COVID shot could potentially boost the flu vaccine’s immune response if both are given in the same arm.

However, giving two shots in one arm can increase the risk of arm soreness, the most common side effect. To explore this in humans, researchers at the University of Melbourne conducted a randomized controlled trial with 56 healthy adults. The study compared giving the Moderna COVID mRNA vaccine and the CSL influenza vaccine in the same arm versus opposite arms.

Participants were randomly assigned to two groups: the “same arm” group received both vaccines in the non-dominant arm (usually the left arm for right-handed people), while the “opposite arm” group had the COVID vaccine in the non-dominant arm and the flu vaccine in the dominant arm. This setup was chosen because the COVID vaccine is more likely to cause a sore arm compared to the flu shot. Researchers collected blood, saliva, and nasal samples, and participants reported on any side effects.

Same Arm vs. Opposite Arm

The trial found no significant differences in key immune responses, such as neutralizing antibodies, whether the vaccines were given in the same arm or separate arms. Secondary analyses suggested a slightly higher immune response to COVID in the opposite arm group.

Nearly all participants reported mild arm soreness. Those in the same-arm group experienced more tenderness in that single arm, while participants in the opposite-arm group had reactions in both arms, particularly in the non-dominant arm that received the COVID vaccine.

What This Means for You

Overall, receiving both vaccines on the same day, whether in one arm or two, provides strong protection against both infections. Choosing opposite arms may slightly improve immune response and reduce soreness in any one arm, but it comes with two mildly sore arms.

For anyone looking to save time, having both vaccines in the same visit is convenient and effective. Most side effects are mild, making the benefits of dual vaccination well worth it.

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5 Popular Herbal Supplements That Could Harm Your Liver

Updated Nov 22, 2025 | 02:00 AM IST

SummaryHerbal and dietary supplements are often seen as natural and safe, but new research highlights potential risks to liver health. Millions of adults regularly use these products, unaware of possible side effects. Learn how to protect yourself and make informed choices while using herbal supplements responsibly.
herbal supplement liver damage

Credits: Canva

Although herbs and plants have been used for medicinal purposes for thousands of years, they have recently gained a surge in popularity, partly thanks to TikTok posts where users highlight the benefits of supplements such as ashwagandha, turmeric, and green tea.

While many consider herbal supplements “natural,” this does not automatically make them safe. Unlike prescription medicines, they do not require approval or review from the U.S. FDA before hitting the market. Users may experience side effects, and some herbs can interfere with medications they are already taking.

Can Herbal Supplements Cause Liver Damage?

Some herbal supplements can harm the liver. A recent study from the University of Michigan suggests that around 15.6 million adults in the U.S., about 5% took at least one herbal supplement in the last 30 days that may be harmful to the liver, known as hepatotoxic. This study was published in JAMA Network Open.

6 Potentially Hepatotoxic Botanical Products

Researchers analyzed data from over 9,500 U.S. adults, with an average age of 47.5, who participated in the National Health and Nutrition Examination Survey (NHANES) between 2017 and 2020. They examined participants’ use of both prescription medications and herbal supplements.

The study focused on six herbal supplements previously linked to liver toxicity:

  • Ashwagandha
  • Black cohosh
  • Garcinia cambogia
  • Green tea extract
  • Red yeast rice
  • Turmeric or curcumin

“Potentially hepatotoxic botanical products contain plant-based ingredients that may contribute to liver damage,” explained Alisa Likhitsup, MD, MPH, a clinical assistant professor in the Department of Internal Medicine at the University of Michigan and lead author of the study.

“How these supplements cause liver injury isn’t fully understood, but it likely involves how the liver metabolizes these products,” she added.

Data from the Drug Induced Liver Injury Network show liver injuries linked to botanical products have risen from 7% in 2004–2005 to 20% in 2013–2014.

‘Natural’ Doesn’t Always Mean Safe

After reviewing the study, Rosario Ligresti, MD, FASGE, chief of Gastroenterology at Hackensack University Medical Center in New Jersey, said that while hepatotoxic botanical products are derived from plants, the lack of oversight and testing means they may do more harm than good.

“They’re unregulated before reaching the market, so it’s not surprising that they pose significant health risks, especially to the liver. They can interfere with the liver’s ability to process and detoxify substances, potentially leading to toxin buildup, inflammation, cell death, and, in severe cases, liver failure,” Ligresti explained, as per Medical News Today.

One notable case involved a 57-year-old woman in New Jersey and New York who developed severe liver damage after taking 2,250 mg of turmeric daily since March 2025 which is far above the WHO’s safe limit of 0–3 mg per kg of body weight per day. She required hospital care for six days at NYU Langone.

Signs of liver damage can include fatigue, nausea, loss of appetite, stomach pain, and dark urine.

Ligresti emphasized that physicians should routinely ask patients about their use of herbal supplements and discuss potential liver risks.

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How Do Weight-Loss Medications Reduce Food Cravings In The Brain?

Updated Nov 21, 2025 | 07:00 PM IST

SummaryHow do weight-loss drugs like tirzepatide reduce food cravings in the brain? Discover how these medications quiet ‘food noise,’ help control appetite, and support healthier eating habits under expert guidance.
weight loss medication food craving

Credits: Canva

A new wave of anti-obesity medications is transforming how people experience hunger. Rather than merely suppressing appetite, these drugs work by gently quieting the brain circuits that constantly drive us to eat.

The obesity medication tirzepatide, marketed as Mounjaro or Zepbound, appears to dampen brain activity linked to food cravings, according to a recent study. Researchers tracked the electrical signals in the brain of someone with severe obesity, who had persistent ‘food noise’ soon after starting the medication.

The study is the first to use electrodes to directly observe how blockbuster GLP-1–mimicking obesity drugs affect brain activity in humans, hinting at how they ease intense food cravings. But how exactly do these weight-loss medications work to reduce the ‘food noise’ in your mind?

We spoke with Dr. Nidhi Khandelwal, a leading Robotic & Laparoscopic Bariatric, Hernia & GI Surgeon | Mumbai MS, FIAGES, FALS (Bariatrics), FALS (Robotics), to understand more.

Can Weight Loss Drugs Suppress Food Craving In Your Brain?

Casey Halpern, a neurosurgeon-scientist at the University of Pennsylvania, and his team did not initially set out to study obesity drugs’ effects on the brain. Their goal was to see if deep brain stimulation—a therapy delivering a mild electrical current directly into the brain, could reduce compulsive eating in people with obesity who did not respond to treatments like bariatric surgery.

For the study, participants had electrodes implanted in their nucleus accumbens, a brain region involved in reward. This area also contains GLP-1 receptors, explains Christian Hölscher, a neuroscientist at the Henan Academy of Innovations in Medical Science, Zhengzhou, China, “so we know GLP-1 influences reward circuits.” The electrodes can both record electrical activity and deliver currents as needed and are already used to treat some epilepsy cases.

For the first two participants, intense food-noise episodes coincided with spikes in low-frequency brain activity, suggesting that these signals could indicate compulsive food cravings.

The third participant, a 60-year-old woman, had just started a high dose of tirzepatide—prescribed for type 2 diabetes—when her electrode was implanted. “We took advantage of this chance because of the excitement around these medications,” Halpern says. In the following months, her urges to binge eat disappeared. “It was remarkable to see the absence of food noise in someone with a long history of cravings,” he adds. “Equally striking was the silence in the nucleus accumbens, as seen in the electrical readings from that area.”

How Do Weight Loss Drugs Help With Food Cravings?

Many people struggling with weight describe a constant ‘buzz’ in their minds, preoccupied with thoughts about their next snack, cravings for sweets, or planning meals even when not hungry. This is often called “food noise.” These medications help quiet that constant chatter.

Dr. Khandelwal explains, “They send signals to the brain similar to what naturally happens after a satisfying meal. People feel full faster, stay satiated longer, and don’t experience the same urge to snack constantly. The mind feels clearer, and the emotional pull of comfort foods becomes easier to manage.”

She also noted another benefit: the ability to make better food choices, like selecting a healthier meal or stopping when full. Goals that once felt impossible now feel achievable and more natural. For many, the biggest change is not only weight loss but also the relief of finally having mental peace from constant cravings, which supports healthier habits.

However, Dr. Khandelwal emphasizes that these medications should only be used under the supervision of a specialist in obesity management.

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