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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More Indians Face Twin Burden of Hypertension and Diabetes After 40: Why Preventive Healthcare Is Important

Updated Aug 10, 2026 | 10:00 PM IST

SummaryA recent hospital-based analysis found that hypertension and diabetes frequently occur together. Nearly 5% of adults had both conditions. Their coexistence increased rapidly from around 40, continued rising until approximately 58 and gradually reached nearly 17% by around age 70.
More Indians Face Twin Burden of Hypertension and Diabetes After 40: Why Preventive Healthcare Is Important

Credit: AI image

India is facing a growing burden of non-communicable diseases (NCDs), with hypertension and diabetes among the major health concerns.

Experts warned that the risk of both conditions rises after 40, often without noticeable symptoms. Increasing age, weight gain, reduced physical activity, stress, dietary habits, and metabolic changes can all contribute to the risk.

Having hypertension and diabetes together is particularly concerning, as their coexistence can increase the risk of heart disease, stroke, kidney damage, retinopathy, and other complications.

Why Risk Rises After 40?

Dr. Santosh Gupta, Associate Director - CTVS, Paras Health Udaipur, told HealthandMe that several factors contribute to the rising risk after 40.

“After the age of 40, the risk of hypertension and diabetes increases due to factors such as changes in metabolism, reduced physical activity, weight gain, stress and dietary habits. What makes both conditions particularly concerning is that they can develop silently, without noticeable symptoms, while gradually affecting vital organs,” he said.

He added that uncontrolled hypertension can damage the heart, brain, kidneys, and blood vessels, while diabetes can affect the kidneys, eyes, nerves, and cardiovascular system.

"When both conditions occur together, the risk of heart disease, stroke and kidney complications becomes even higher,” Dr. Gupta added.

Because both conditions can remain silent for years, people may have high blood pressure or blood sugar without knowing it.

Also read: Breastfeeding Can Help Reduce Mothers' Risk of Type 2 Diabetes, Breast Cancer and More

Hypertension And Diabetes Often Coexist

A recent hospital-based analysis found that hypertension and diabetes frequently occur together, with their coexistence rising sharply from around age 40 among Indians.

The study, conducted by the Department of Clinical Research and Preventive Health Program at Max Healthcare, analyzed health records of more than 56,000 adults who underwent preventive health check-ups between January 2021 and December 2024.

Nearly 5% of adults had both conditions. Their coexistence increased rapidly from around 40, continued rising until approximately 58 and gradually reached nearly 17% by around age 70.

People with diabetes were nearly four times more likely to have hypertension, while those with hypertension were about 2.5 times more likely to have diabetes.

Dr. Abhaya Indrayan, Biostatistics Consultant, Max Healthcare, said the findings support screening for both conditions rather than assessing them separately.

Why Screening After 40 Matters

Read More: Confused By Your Cholesterol Report? Here's What LDL And ApoB Really Mean

Experts said that preventive healthcare should go beyond checking for individual diseases. Adults over 40 should routinely assess key cardiometabolic risk factors, including blood pressure and blood sugar.

Screening can help detect hypertension, diabetes or prediabetes early, when lifestyle changes and treatment can help prevent or delay complications.

“This is why regular screening after 40 is important, even for individuals who feel completely healthy. A routine blood pressure check, fasting blood glucose or HbA1c test can help identify hypertension, diabetes or prediabetes at an early stage, when timely lifestyle changes and medical intervention can prevent or delay complications,” Dr. Gupta said.

“Screening should not be viewed only as a diagnostic exercise; it is an opportunity to understand one’s health risks and take corrective measures before the disease begins to cause irreversible organ damage,” he added.

How To Lower The Risk

Preventive care also involves addressing modifiable risk factors. Regular physical activity, maintaining a healthy weight, limiting salt, sugar and highly processed foods, getting adequate sleep and avoiding tobacco can help lower the long-term risk.

For those already diagnosed with hypertension or diabetes, regular monitoring and adherence to prescribed treatment are important to reduce the risk of complications.

With the risk of both conditions rising after 40, experts recommend making routine health checks part of regular healthcare—even when there are no obvious symptoms.

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Delhi Sees Nearly 6x Rise In H1N1 Cases: How Is It Different From Other Respiratory Infections?

Updated Aug 10, 2026 | 05:10 PM IST

SummaryH1N1 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.
Delhi Sees Nearly 6x Rise In H1N1 Cases: How Is It Different From Other Respiratory Infections?

Credit: AI Image

Amid the ongoing monsoon season, Delhi-NCR is seeing a rise in H1N1 influenza cases, with Delhi reporting 1,344 cases so far this season.

The figure is nearly six times higher than the 229 H1N1 cases recorded during the same period last year, The Times of India reported.

According to health officials, Delhi recorded around 4,000 influenza cases last year, most of them caused by H3N2. This year, H1N1 is the dominant strain. Both H1N1 and H3N2 are subtypes of Influenza A and spread mainly through respiratory droplets.

What Is H1N1 and Why Is Testing Important?

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.

Dr Aijaz Ilmi, Senior Consultant – Metabolic Diseases, Pacific OneHealth Hospital, told HealthandMe that testing is particularly important when fever or respiratory symptoms persist or worsen, especially among older adults, young children, pregnant women and people with diabetes, obesity, heart or lung disease, or compromised immunity.

“With the current rise in H1N1 cases in Delhi, we are also seeing other seasonal respiratory infections, including Influenza A and B, COVID-19, RSV and other respiratory viruses. At the same time, the monsoon season brings an increased risk of mosquito-borne illnesses such as dengue.

“The key message is, don’t panic, but don’t dismiss a persistent fever as ‘just a viral’. Early recognition is particularly important in vulnerable individuals.”

H1N1 vs Other Respiratory Infections: How Are They Different?

H1N1 can be difficult to distinguish from other respiratory infections because many of them cause similar symptoms.

  • H1N1 and other seasonal influenza strains: Both can cause sudden fever, cough, sore throat, headache, body aches and fatigue. Symptoms alone generally cannot determine whether the infection is H1N1 or another influenza strain.
  • COVID-19: COVID-19 can cause fever, cough, sore throat, congestion and fatigue. Some people may also experience changes in or loss of taste or smell, while gastrointestinal symptoms can occur.
  • RSV: RSV commonly causes a runny nose, cough and wheezing. It can be more severe in infants, older adults and people with certain underlying conditions. In young children, it can cause bronchiolitis and breathing difficulties.
  • Dengue: During the monsoon, dengue can also cause fever, headache, body aches and fatigue, which may initially resemble a viral respiratory infection. However, dengue is spread by mosquitoes rather than respiratory droplets and does not typically cause cough or sore throat.
Dr Amit Prakash Singh, Consultant - Internal Medicine at The CK Birla Hospital, Delhi, told HealthandMe that because symptoms overlap, they cannot confirm the infection. Molecular or antigen-based tests can help identify the virus, particularly in high-risk patients or those with severe or persistent symptoms.

How Can H1N1 and Other Infections Be Prevented?

Dr Sharwari Sudhir Dabhade, Consultant - Internal Medicine, Diabetology & Endocrinology, Madhukar Rainbow Children's Hospital, told HealthandMe that prevention should focus on reducing exposure and maintaining good hygiene. Other measures to reduce transmission include:

  • Washing hands frequently.
  • Covering mouth and nose while coughing or sneezing.
  • Maintaining good indoor ventilation.
  • Avoiding crowded or poorly ventilated places when respiratory infections are circulating.
  • If you have respiratory symptoms, limit close contact with others and wear a mask.
  • Getting vaccinated against influenza, particularly if you are an older adult, young child or have an underlying health condition.
  • Prevent mosquito breeding and take precautions to avoid mosquito bites to reduce risk of dengue.

When Should You Seek Medical Help?

Most viral respiratory infections recover with supportive care. However, should seek prompt immediate medical assessment in cases of

  • breathlessness
  • persistent high fever,
  • chest pain,
  • confusion,
  • dehydration,
  • falling oxygen saturation
  • significant worsening of weakness.

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The Gut-Brain Connection: Study Says IBD Patients May Experience Depression & Anxiety Years Before Diagnosis

Updated Aug 10, 2026 | 04:00 PM IST

SummaryA recent study indicates that patients with inflammatory bowel disease are more likely to get diagnosed with mental health issues like depression and anxiety
IBD Linked To Higher Risk Of Depression And Anxiety Years Before Diagnosis

Credit: AI

People with inflammatory bowel disease (IBD) may face a higher risk of depression, anxiety and other psychiatric disorders years before they are diagnosed with the gut condition, a new study has discovered.

The study, published in Clinical Gastroenterology and Hepatology, found that the risk of psychiatric disorders began rising two to three years before an IBD diagnosis, peaked shortly after diagnosis and remained elevated for as long as a decade.

Researchers from Karolinska Institutet and other Swedish institutions analysed data from 43,862 people with IBD, comparing them with nearly 179,000 individuals from the general population and more than 26,000 IBD-free full siblings.

The sibling comparison was key as it helped researchers examine whether shared genetic or early-life environmental factors could explain any association.

Risk Of Mental Health Issues Increase Before IBD Diagnosis

Also read: Monsoon Gut Health: Addressing The Rise In Rotavirus And Viral Gastroenteritis Cases

The study found that the risk of developing any mental health disorder was already 15% higher two years before IBD diagnosis. It increased further around the time of diagnosis, reaching a roughly 50% higher risk within the first six months.

Although the risk reduced afterwards, it remained about 19% higher even 10 years after diagnosis. Major depressive disorder, anxiety disorders and substance misuse accounted for much of the increase.

Antidepressant and anti-anxiety medication use also began rising around a year before the IBD diagnosis.

Researchers called for mental health screening to begin early, including during the initial gastroenterology evaluation.

“It is time to actively manage psychiatric conditions in patients with IBD,” said Jiangwei Sun, PhD, the study’s lead author.

Why Depression And Anxiety Appear Before IBD Is Diagnosed?

Also read: Following A Western Diet? Changes In Your Gut Bacteria Could Increase Colon Cancer Risk

IBD includes Crohn’s disease and ulcerative colitis, autoimmune conditions that cause inflammation in the digestive tract.

One possible explanation is the gut-brain axis, the two-way communication system connecting the digestive system and brain.

Inflammation, changes in gut bacteria and abnormal immune activity may affect brain function and overall mood. At the same time, stress and psychological distress can affect the gastrointestinal symptoms.

But researchers caution that the study merely shows an association, not proof that IBD directly causes depression or anxiety.

Some people may experience subtle or unexplained gastrointestinal symptoms before receiving an official diagnosis, while the uncertainty and disruption caused by chronic symptoms could also affect mental health.

Mounting Evidence

The findings follow previous research that shows psychiatric symptoms can surface before the patient is diagnosed with IBD.

A 2023 study examining longitudinal health records found that anxiety and depression occurred more frequently among people who were later diagnosed with IBD.

In a 2024 systematic review and meta-analysis, it was observed that patients with a history of depression may have a small-to-moderate increased risk of subsequently developing IBD, suggesting that the relationship between the gut and mental health could work in both directions.

The new findings therefore signal that mental health symptoms may sometimes arrive years before IBD itself is formally diagnosed in patients.

For doctors, researchers say this highlights the need to treat IBD as more than a digestive disease, with psychological support and screening considered part of long-term care.

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