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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H1N1 Flu Rising in India: Why Heart Patients Need to Watch

Updated Aug 12, 2026 | 09:43 PM IST

SummaryAlthough H1N1 influenza primarily affects the respiratory tract, the infection can also put additional strain on the heart in some people, particularly those with a chronic history of cardiovascular disease.
H1N1 Flu Rising in India: Why Heart Patients Need to Watch

Credit: AI generated

Influenza strain H1N1, formerly known as swine flu, is rising significantly in India, with deaths also being reported in some states.

H1N1 is a subtype of Influenza A and can cause sudden fever, cough, sore throat, headache, body aches and fatigue. These symptoms can overlap with those of other seasonal influenza strains, COVID-19 and respiratory syncytial virus (RSV), making it difficult to identify the infection based on symptoms alone.

H1N1 Cases and Deaths Reported in States

Delhi: According to official data, Delhi has reported 1,349 confirmed H1N1 infections. No official deaths have been reported.

Kerala: A total of 2,468 influenza cases were recorded in the state in July, with 24 deaths reported during the month. The total number of cases recorded in the state this year stands at 5,519, with 60 deaths reported.

Maharashtra: The state has reported 25 laboratory-confirmed H1N1 cases, including a major spike of 15 cases in July. One confirmed death was officially verified by the Nagpur Municipal Corporation (NMC) Death Audit Committee.

Gujarat: H1N1 activity is also being reported, with Ahmedabad currently seeing a rise in cases.

Although H1N1 influenza primarily affects the respiratory tract, the infection can also put additional strain on the heart in some people, particularly those with a chronic history of cardiovascular disease, experts told HealthandMe.

How H1N1 Can Strain the Heart

Fever, dehydration, increased levels of carbon dioxide in the body, decreased oxygen levels and the body’s inflammatory response can increase the workload on the heart during an H1N1 infection.

This added strain may be more concerning for people who already have cardiovascular disease, said Dr. Praveen Raman Mishra, Associate Consultant, Institute of Cardiac Sciences at ShardaCare – Healthcity.

Heart Problems Linked to H1N1

Some H1N1 influenza patients may experience cardiovascular complications, including:

  • Inflammation of the heart
  • Abnormal heartbeats
  • Worsening of heart failure
These problems may occur as the body responds to the infection and the heart faces increased demands.

Dr. Saurabh Gupta, Associate Director, Internal Medicine, Yashoda Medicity, added that H1N1 infection may cause fluctuations in heart rhythm or inflammation associated with the heart.

“In some circumstances when suffering from the H1N1 virus, although the initial symptoms of the virus may be those shared with the normal flu, such as temperature, aches and cough, those with pre-existing heart conditions should be more vigilant whilst they’re recuperating,” he told HealthandMe.

“As the infection puts more work on the body, you can find that previous heart problems are more noticeable,” he added.

Warning Signs to Watch For After H1N1

The experts noted that people recovering from H1N1 should seek medical attention if they develop symptoms such as:

  • Severe chest pain
  • Shortness of breath
  • A high or fluttering pulse
  • Sudden faintness
  • Severe weakness
According to Dr. Mishra, these symptoms could indicate a problem involving the cardiovascular system. Early evaluation is important because such complications can be treatable when detected promptly.

Who Should Be Particularly Careful?

People with a chronic history of cardiovascular disease may face greater strain on the heart during H1N1 infection.

Monitoring symptoms during recovery and seeking medical attention when concerning symptoms develop can help identify cardiovascular problems early.

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Combining GLP-1 & Hormone Therapy During Menopause? Know About Its Benefits And Side Effects

Updated Aug 12, 2026 | 07:00 PM IST

SummaryA recent study has observed that menopausal women who took GLP-1 drugs and hormone therapy together could lose more weight.
Combining GLP-1 & Hormone Therapy During Menopause? Know About Its Benefits And Side Effects

Credit: AI

For many women, menopause can bring a string of uncomfortable symptoms like hot flashes, sleep problems, changing body composition and weight gain.

Now, researchers are looking at whether combining GLP-1-based weight-loss medicines with menopausal hormone therapy (MHT) could offer greater benefits, particularly for women struggling with obesity after menopause.

A recent Mayo Clinic study, published in The Lancet Obstetrics, Gynaecology & Women's Health, found that postmenopausal women taking tirzepatide along with hormone therapy lost about 35% more weight than those taking tirzepatide alone.

What Are The Study's Findings?

Researchers studied 120 postmenopausal women with overweight or obesity who had been taking tirzepatide for at least 12 months. Forty women were also using MHT, while 80 were not.

Women taking both treatments lost around 17-19% of their body weight, compared with about 14% among those taking tirzepatide alone. About 45% of women on the combination achieved at least 20% weight loss, compared with 18% in the tirzepatide-only group.

“This study provides important insights for developing more effective and personalized strategies for managing cardiometabolic risk in postmenopausal women,” said Dr Regina Castaneda, first author and Mayo Clinic researcher.

However, this was just an observation in the study, not a randomized clinical trial. Therefore, it cannot prove that hormone therapy itself caused the additional weight loss.

“It is possible that women using hormone therapy were already engaged in healthier behaviors, or that menopause symptom relief improved sleep and quality of life,” said Dr Maria Daniela Hurtado Andrade, senior author of the study.

Also read: Postmenopausal Women May Face More Severe Dry Eye Disease; How Do Hormones Contribute?

Could The Combination Work?

During menopause, declining oestrogen levels can change fat distribution, appetite, metabolism and muscle mass. GLP-1 medicines, meanwhile, reduce appetite and slow stomach emptying, helping with weight management.

Researchers believe there could also be a biological interaction between oestrogen and GLP-1 signalling. “Preclinical data suggest a potential synergy, with estrogen appearing to enhance the appetite-suppressing effects of GLP-1,” Castaneda said.

Earlier research has also suggested greater weight loss among postmenopausal women using semaglutide alongside hormone therapy.

A 2026 review similarly concluded that GLP-1 medicines may help reduce weight and abdominal fat in menopausal women, but larger studies are needed.

Also read: Experimental Menopause Drug Shows Promise Mid-Stage Trial, Reduces Hot Flashes By 83%

Are There Any Side Effects Of Combining These Drugs?

GLP-1 medicines may cause nausea, vomiting, diarrhoea, constipation, abdominal pain and reduced appetite. These effects often surface when the dose is increased.

Hormone therapy has its own side-effects and it is also not suitable for everyone. Depending on the patient's medical history, MHT can increase the risk of complications like blood clots and stroke.

Hormone therapy should not be started simply to fuel weight loss from a GLP-1 drug. It is primarily used to treat certain menopause symptoms and should be prescribed after considering a woman's age, symptoms, medical history and individual risks.

As Hurtado Andrade noted, researchers now want to determine whether the combination offers benefits beyond weight loss, including improvements in cardiometabolic health.

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Why Your Thyroid Test Results Can Vary Between Labs?

Updated Aug 12, 2026 | 03:00 PM IST

SummaryThyroid test results can vary between laboratories due to differences in testing methods, equipment, reference ranges, and sample handling, without necessarily indicating a change in thyroid function.
Why Your Thyroid Test Results Can Vary Between Labs?

Credit: AI

It can be confusing and sometimes alarming to receive different thyroid test results from two different laboratories, especially when both tests are done on the same day. A slight difference in values does not necessarily mean that your thyroid function has suddenly changed. In many cases, the variation is due to differences in how the tests are performed rather than a change in your health.

The Laboratory Can Make A Difference

One of the biggest reasons for varying results is the laboratory itself. Accredited laboratories, such as NABL-certified labs, follow stringent quality-control measures, use standardised testing protocols and have trained personnel to handle samples correctly. Laboratories with less rigorous quality standards may produce results that are less consistent.

Different Equipment Can Produce Different Results

The equipment and testing methods used can also differ from one laboratory to another. Different analysers, calibration techniques and testing kits can produce slightly different values for thyroid hormones such as TSH, T3, T4, Free T3 and Free T4.

Even the reference ranges printed on reports may not be identical because each laboratory establishes its own normal range based on the equipment used and the population it serves.

Also read: UK Approves Eli Lilly’s Foundayo: Is the GLP-1 Pill Better Than Wegovy, Mounjaro?

The Time Of Your Test Matters

The timing of the test is another important factor. Thyroid-stimulating hormone (TSH) naturally fluctuates throughout the day. It is generally higher during the early hours of the morning and gradually falls as the day progresses.

As a result, a blood sample collected in the afternoon may show a lower TSH level than one collected early in the morning.

Stress, Sleep And Medication Can Affect Results

Lifestyle and biological factors can also influence thyroid hormone levels. Stress, poor sleep, recent illness, medications and even eating before the test may affect the results.

For people taking thyroid medication, blood samples should ideally be collected in the morning on an empty stomach and before taking the daily dose. Testing after medication may temporarily alter hormone levels and make interpretation more difficult.

Also read: Why Women Want Hormonal Health Care, Not Just Pregnancy Care

Biotin And Other Medicines Can Interfere With Thyroid Tests

Certain supplements and medications can interfere with thyroid tests as well. Biotin, commonly found in hair and nail supplements, can falsely lower TSH levels while increasing Free T3 and Free T4 values.

Medications such as amiodarone, glucocorticoids, dopamine and heparin may also affect thyroid hormone measurements. During pregnancy, hormonal changes, particularly increased levels of human chorionic gonadotropin (hCG), can naturally alter TSH values.

Even Sample Handling Can Affect The Report

Laboratory handling also plays a role. Delays in processing, improper storage temperatures, differences in centrifugation timing or sample-handling errors can influence the final result.

In some individuals, thyroid autoantibodies may interfere with laboratory assays, potentially leading to inaccurate Free T3 and Free T4 measurements.

Also read: Silent Neck Swellings: Why An Unusual Lump Should Never Be Ignored

Should You Repeat A Thyroid Test?

Because of these variables, experts recommend getting thyroid tests done at the same accredited laboratory whenever possible. This allows doctors to compare results more reliably over time.

If a thyroid value is only mildly abnormal or falls within a borderline range, it may often be advisable to repeat the test before making a diagnosis or starting lifelong medication.

Ultimately, thyroid test reports should never be interpreted in isolation. Doctors consider the patient's symptoms, medical history, physical examination and repeat test results before deciding on treatment.

Consistency in where and how the test is performed can help avoid unnecessary anxiety and support more accurate clinical decisions.

By Dr Shaheen Guy, General Physician, Saifee Hospital, Mumbai

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