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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Hormone Replacement Therapy May Lower Dementia Risk In Women, Shows Study

Updated Aug 27, 2026 | 10:24 PM IST

SummaryWomen who used HRT had a 26% lower risk of dementia compared with non-users. Those who started menstruating later or experienced menopause earlier also had a 16% lower risk of dementia with HRT use.
Hormone Replacement Therapy May Lower Dementia Risk In Women, Shows Study

Credit: iStock

Women have a higher overall risk and prevalence of Alzheimer’s disease and certain other forms of dementia, partly because they tend to live longer than men and because of changes in estrogen levels after menopause.

A new study by researchers from the University of East Anglia (UEA) and the University of Exeter suggests that hormone replacement therapy (HRT) may be associated with a lower risk of dementia in some women.

“Dementia affects millions of people worldwide, with women making up almost two-thirds of Alzheimer’s disease cases, the main form of dementia. As populations age, understanding how sex-specific factors influence dementia risk is increasingly important,” said Prof Anne-Marie Minihane from UEA’s Norwich Medical School, who led the study.

HRT Linked To Lower Alzheimer’s Risk

The study, published in the journal Alzheimer’s & Dementia, analyzed health data from more than 180,000 postmenopausal women in the UK.

The findings showed:

  • 16% lower risk of Alzheimer’s disease among women who had used HRT compared with those who had never used it.
  • 10% lower risk of dementia overall was associated with HRT use.
  • 26% lower risk of any dementia among women who had undergone surgical menopause and used HRT.
  • 16% lower risk of any dementia among women with lower lifetime estrogen exposure due to later menstruation or earlier menopause.

Which Groups Benefited More From HRT?

The association between HRT use and lower dementia risk was stronger in certain groups. These include:

  • Women who underwent surgical menopause: Those who used HRT had a 26% lower risk of dementia compared with non-users.
  • Women with lower lifetime estrogen exposure: Those who started menstruating later or experienced menopause earlier had a 16% lower risk of dementia with HRT use.
  • APOE4 carriers: The association between HRT use and lower dementia risk was stronger among women carrying the APOE4 gene variant, a known risk factor for Alzheimer’s disease.
  • Women who started HRT between ages 46 and 56: This group experienced the greatest reduction in dementia risk.
  • Timing may matter: The findings support the “critical window” hypothesis, suggesting HRT may offer greater benefits when started closer to the menopausal transition rather than later in life.

Could HRT Support Personalized Care?

The researchers said the findings add to growing evidence that the effects of hormone therapy on brain health are complex and may vary between women.

“While HRT has long been prescribed primarily to relieve menopausal symptoms such as hot flushes and night sweats, this work suggests it may also play a role in long-term cognitive health for some women,” Prof Minihane said.

The latest findings build on previous research from UEA, which found that HRT use was associated with better memory, cognition and larger brain volumes later in life among women carrying the APOE4 variant.

The team said the findings could help support more personalized approaches to HRT prescribing, taking into account factors such as menopause type, genetic risk, lifetime hormone exposure and age at HRT initiation.

Prof David Llewellyn of the University of Exeter Medical School said the findings help identify which women may be more likely to benefit from HRT and when treatment may have the greatest effect.

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Can Stress Trigger Psoriasis Flare-Ups? Understanding The Mind-Skin Connection

Updated Aug 27, 2026 | 01:00 PM IST

SummaryStress can trigger or worsen psoriasis flare-ups by influencing immune and inflammatory responses, highlighting the connection between psychological stress and skin health.
Can Stress Trigger Psoriasis Flare-Ups? Understanding The Mind-Skin Connection

Credit: AI

The association between stress and psoriasis is one of the better-documented cases of the mind and skin connection within dermatology. Consistent across studies, at least in most case series, there is a sizable proportion of patients who experience an important stressful event within the weeks prior to onset or flare-up.

The mechanism is quite clear cut. While the skin is often seen as being passive, it is far from it. Skin itself is immunologically active, having a stress response system of its own, able to produce corticotropin-releasing hormone and cortisol independently from adrenals.

The Mind-Skin Connection

Under prolonged stress, the shift happens in the hypothalamic-pituitary-adrenal axis, leading to a reconfiguration of the immune response towards inflammatory pathways, specifically IL-17 and IL-23 pathway which was targeted by most biologics developed up to now.

Neuro-endocrine innervations lead to the release of neuropeptides such as substance P, attracting inflammatory cells while lowering the threshold of itching. Chronic stress also impairs barrier recovery process, relevant for a disease where the slightest skin damage leads to a plaque formation.

So whenever a patient claims stress caused her flare-up, she is describing an actual immunological phenomenon.

And the cycle, which is the part that entraps people.

And here lies the complexity, the place where I believe most of the articles end prematurely.

Also read: ‘Sunscreen Is A Health Essential’: UK Skin Cancer Survivor Urges Govt To Scrap Tax

Stress Aggravates Psoriasis

Then the psoriasis becomes the source of stress. Highly visible plaques on hands, scalp or face are hard to hide within a culture where we greet, eat and worship with our hands. Patients start dressing in ways that conceal their plaques. They avoid public showers, salons, wedding events. Itch affects their sleeping habits, causing higher inflammation levels.

Then come the questions patients do not usually disclose unless specifically asked. The shame. Some patients have experienced people wondering whether they could catch the condition. Some of them have been asked to leave the salon where they went. This is not just an annoyance, but also a hurt, directly feeding back into the loop.

The prevalence of depression and anxiety in psoriasis is much higher than among healthy people. Moreover, these problems cannot be explained only by a reaction to one's appearance. The same inflammatory mediators, which cause psoriasis, are now associated with depression. Therefore, psoriasis and depression can be two symptoms of one inflammatory condition.

Also read: Mpox Spreads in Guinea-Bissau, Half Of Suspected Cases Are Children

What Really Helps?

Here I need to be very careful, since the idea that stress provokes psoriasis can be twisted into the belief that the patient has caused his/her own illness. But it is not true and is insulting to people suffering from the condition. It should be said again that psoriasis is a genetically based immune disorder. It is stress that exacerbates the disease.

Within this framework, stress management techniques are useful and there is the trial evidence for their efficiency. In one study, mindfulness-based intervention helped to improve the outcome and even accelerated clearance with phototherapy.

Physical exercise has an independent anti-inflammatory effect and treats metabolic syndrome associated with psoriasis. Sleeping is an obligatory factor because sleep deprivation increases the level of cytokines that we need to suppress. Cognitive behavioral therapy helps people to cope with itching-scratching cycle.

There is no doubt that alcohol and smoking make psoriasis worse, although they are usually used as a coping strategy in response to stress. They serve as an additional burden on health.

All of this is important but not an alternative to treatment. Topicals, phototherapy, systemic medications, and biological agents still remain the core of the treatment regimen. Stress management is only an adjunct, and I always remind my patients about it so that they never feel guilty for taking medicine.

Treat The Whole Person

Now I ask two questions at each review of psoriasis. How much of the body surface area is affected and how much of the person's life does it occupy. The answer to these questions often does not coincide.

I saw patients with rather small involvement of the skin surface, whose psoriasis completely ruined their self-esteem. And I met patients with large involvement who coped with the disease perfectly.

Body surface area does not measure suffering. If we treat only what we can see, we will treat half of the disease.

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H1N1 Cases, Deaths Rise Across India: States Reporting Surge, Red Flags to Know

Updated Aug 26, 2026 | 10:29 PM IST

SummaryICMR Director General Dr Rajiv Bahl has said H1N1 accounts for nearly 98% of Influenza A cases currently detected in India. Delhi, Maharashtra, Uttarakhand is reporting a significant surge in H1N1 cases and deaths.
H1N1 Cases, Deaths Rise Across India: States Reporting Surge, Red Flags to Know

Credit: AI Image

H1N1 cases are rising across several Indian states, with infections, hospitalisations and deaths being reported. However, the Indian Council of Medical Research (ICMR) has said the increase is not unusual and that no new strain is driving the current rise.

The ICMR has clarified that the circulating Influenza A (H1N1) pdm09 viruses have been present in India since 2025 and that no new strain has been identified.

ICMR Director General Dr Rajiv Bahl has said H1N1 accounts for nearly 98% of Influenza A cases currently detected in India, while H3N2 accounts for around 2-3% of cases.

Health authorities have urged people not to panic but to remain alert, particularly if symptoms become severe or persist.

States Reporting H1N1 and Influenza Cases

Delhi

Delhi has reported 138 new H1N1 cases in the last 24 hours, taking the cumulative number of H1N1 cases this year to 2,446, the Delhi government said on Wednesday.

The total number of Influenza A cases has reached 3,177 as the city continues to see a rise in seasonal influenza infections.

Maharashtra

Maharashtra is witnessing a significant surge in Influenza A (H1N1) cases, with the 2026 tally already surpassing the total recorded throughout the previous year.

As of August 21, the state had reported 1,109 H1N1 cases, compared with 942 cases in all of 2025.

Mumbai and Pune remain the primary centres of reported infections, together accounting for around 65% of the state's total cases.

Uttarakhand

Uttarakhand has reported 49 confirmed H1N1 cases and five deaths as of late August 2026, prompting a heightened health alert.

The state has also reported 103 dengue cases, including 49 confirmed cases from Dehradun.

Karnataka

Karnataka has recorded 4,212 laboratory-confirmed influenza cases, including H1N1 cases, across 32 districts since January, with the majority of active cases concentrated in Bengaluru.

That compares with 4,583 cases in 2025 and 3,903 cases in 2024.

Kerala

Kerala has reported 7,421 influenza cases and 88 deaths this year, with most fatalities reported among people over 50.

These figures refer to influenza overall and should not be treated as H1N1-specific cases or deaths.

What Does H1N1 Usually Feel Like?

According to the Ministry of Health and Family Welfare, fever and systemic symptoms generally last around three days, although they can persist longer. Cough and weakness may continue even after the fever settles.

Dr GC Khilnani, Chairman, PSRI Institute of Pulmonary, Critical Care & Sleep Medicine, PSRI Hospital, New Delhi, told HealthandMe that common symptoms include body aches, sore throat, headache and fever, which can sometimes be high-grade.

Nausea, vomiting and occasional chest pain may also occur. The illness can be relatively short-lived and may last around three to five days in many cases.

H1N1 Red Flags You Shouldn't Miss

Certain symptoms should not be managed casually at home. These include:

Fever accompanied by breathlessness

Chest pain

Increasing weakness

Confusion

Bluish lips or nails

A noticeable fall in oxygen levels

These symptoms may indicate more serious respiratory involvement and require prompt medical assessment.

Who Needs to Be Particularly Cautious?

Although influenza can affect people of any age, certain groups are more likely to develop severe illness. These include young children, older adults, pregnant women and people with asthma or other chronic lung conditions, heart disease, diabetes or kidney disorders.

People with weakened immune systems are also at greater risk of complications. This includes cancer patients, particularly those receiving chemotherapy or other treatments that suppress immunity.

“An oncology patient may not always develop a dramatic set of symptoms at the beginning. Chemotherapy can affect blood counts and reduce the body's ability to mount an effective response to infection. That is why a new fever or respiratory symptom during treatment deserves earlier attention than it might in an otherwise healthy person,” says Dr Ankur Nandan Varshney, Sr. Medical Oncologist, Medanta Hospital, Noida, told HealthandMe.

Which Tests Are Actually Needed?

Not everyone with a cough and fever needs an H1N1 test. Testing is generally guided by symptoms, severity, risk factors and the clinical situation.

If the doctor suspects influenza and confirmation is needed, testing is usually done using a respiratory sample collected through a nasal or nasopharyngeal swab. Molecular methods such as RT-PCR can identify the influenza virus and help confirm the diagnosis.

“For a cancer patient, I would not look at the H1N1 report in isolation. A CBC with differential, particularly the neutrophil count, can be clinically important during chemotherapy. Depending on symptoms, oxygen saturation and examination findings, the doctor may also recommend a chest X-ray or CT scan to look for pneumonia or other lung complications,” explains Dr Varshney.

Don't Wait for Symptoms to Become Severe

People who are more susceptible to complications should seek medical advice early rather than relying on repeated home tests or taking medicines without guidance.

While many seasonal influenza infections improve on their own, individuals with weakened immunity or other underlying risk factors need closer monitoring and should contact their doctor promptly if symptoms appear or start getting worse.

“Especially in patients undergoing cancer treatment, the aim should be to identify deterioration early rather than wait until breathing becomes difficult,” said Dr Varshney.

How Can You Prevent H1N1 Infection?

Simple precautions can help reduce the spread of seasonal influenza:

Wash your hands regularly with soap and water.

Cover your mouth and nose when coughing or sneezing.

Avoid close contact with people who are sick.

Stay home when experiencing flu-like symptoms.

Improve ventilation in shared indoor spaces.

Avoid touching your eyes, nose and mouth with unwashed hands.

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