We all must have come across the phase: this is why women live longer than men. These are all over the social media, where men are performing more often than not, some experiments, without gears, just for fun, "in the name of science". The caption reads: this is why women live longer. However, is there really a science to it, other than the fact that women choose to do things more safely?

In the United States, women have a life expectancy of about 80, whereas men have 75. Women outlive men and this holds true regardless of the country women live, the money they make, and other factors. In fact, it is true for most other mammals too.

Dr Dena Dubal, a professor of neurology at the University of California, San Francisco told the New York Times, "It is a very robust phenomenon all over the world, totally conserved in sickness, during famines, during epidemics, even during the times of starvation."

But what are the reasons? These reasons are often more complicated and less established. It is important to note that only because women are outliving men does not mean they are living a better life. In fact, women tend to have shorter health spans, which means the number of healthy years in a person's life is less in women than men, confirmed Bérénice Benayoun, an associate professor at the U.S.C. Leonard Davis School of Gerontology.

As per a 2021 study titled, Sex differences in frailty: Comparisons between humans and preclinical models, found that women are more physically grail than men in old age. They are also more vulnerable, especially after menopause and are at more risk of developing cardiovascular issues and Alzheimer's disease because of age.

The key is in figuring out what makes one sex more resilient or vulnerable.

Genetics

For things which do not find easy explanations, scientists look for their answers in genes. Many research, including a 2020 study titled, The sex with the reduced sex chromosome dies earlier: a comparison across the tree of life, suggests that the XX set of female sex chromosomes may impact longevity. However, there has not been any clarity on how it affects longevity.

Another 2018 study titled, Female XX sex chromosomes increase survival and extend lifespan in aging mice, which was conducted by Dr Dubal's lab, looked at genetically manipulated mice with different combinations of sex chromosomes and reproductive organs. It was found that those with two X chromosomes and ovaries lived longest, followed by mice with two X chromosomes and testes. Mice with XY chromosomes had shorter life spans.

"There was something about the second X chromosome that was protecting the mice from dying earlier in life, even if they had testes. What if there was something on that second X chromosome that was in some ways a sprinkle of the fountain of youth," says Dr Dubal. While scientists have not yet looked at this factor in humans, Dr Dubal suggests that humans have the same hormones and sex chromosomes, and similar reproductive system that could corroborate the similar findings in people.

Hormones

Plenty research has shown that estrogen is responsible for longevity also effect on the immune system. The data also shows that before menopause, the female immune system tends to do better. In fact Dr Benayoun said that males tend to do much worse in response to infection.

Another 2017 study titled, Ages at Menarche and Menopause and Reproductive Lifespan As Predictors of Exceptional Longevity in Women: The Women's Health Initiative, found that women who experienced menopause later in life over the age 50 lived longer than those who experienced it earlier.

Lifestyle and Behavior

There are also disparity in behavioral patterns between men and women. This includes smoking, drinking heavily, which can contribute significantly to mortality. Women also have more "health promoting behavior", believe experts. Women are also more likely to socialize than men and thus it protects them from detrimental effects of social isolation and loneliness. In fact, a 2023 analysis published in Jama Network, titled, Widening Gender Gap in Life Expectancy in the US, 2010-2021, found that women are less likely to die by drug overdose or suicide.

Sleep disturbances are among the most debilitating symptoms of Alzheimer’s disease. It often appears years before significant memory decline and other symptoms.

A new study from researchers at the University of Kentucky suggests that this sleep loss may not be permanent.

Instead, it could be driven by an immune response in the brain that may be reversible, sparking hope for new treatments.

Published in the journal Alzheimer’s & Dementia, the study found that brain immune cells called microglia, rather than amyloid plaques themselves, are the primary cause of sleep disruption in Alzheimer’s disease.

In mouse-based trials, researchers were able to restore more than two hours of sleep per day by temporarily removing these immune cells, without reducing amyloid plaques.

Can Sleep Be Restored In Alzheimer’s Patients?

For years, scientists believed that sleep problems in Alzheimer’s were caused by the accumulation of amyloid plaques or the gradual death of brain cells. However, this study points in a different direction.

Researchers discovered that when amyloid plaques begin forming in the brain, they activate microglia, the brain’s resident immune cells.

Instead of protecting the brain, these cells cause inflammation that keeps brain circuits active, preventing sleep.

Using a drug called pexidartinib (PLX3397), the researchers temporarily depleted around 87% of microglia in Alzheimer’s mouse models.

This restored over two hours of daily sleep, particularly non-rapid eye movement (NREM) sleep, which is essential for tissue repair, memory strengthening, and clearing waste products from the brain.

Notably, the improvement occurred without changing amyloid plaque levels, suggesting that inflammation is manageable.

Also read: Captain ‘Sully’ Sullenberger, ‘Miracle On The Hudson’ Pilot, Reveals Early-Stage Alzheimer’s Diagnosis

'Paradigm Shifting' Findings

Lead researcher Dr. Shannon L. Macauley, associate professor of physiology at the University of Kentucky College of Medicine, said, “Basically, we showed that it is not the plaques themselves, or solely dysfunctional neurons, that cause sleep loss but actually microglia.

Microglia are immune cells that, when they respond to plaques, kick off this elaborate cascade of inflammation, as if the microglia are partying all night, and keeping the brain awake.”

She also highlighted why losing restorative sleep can accelerate disease progression.

“That restorative sleep is super important for physical repair, learning and memory and washing out the toxins of the day. When Alzheimer’s patients lose this stage, they lose their brain’s primary cleaning cycle, creating a feed-forward loop that may drive further damage,” she explained.

First author Dr. Nicholas J. Constantino said one of the biggest surprises was that sleep problems did not worsen as amyloid plaques increased.

“I expected that as plaque burden became more severe, sleep disruption would also worsen. The disruptions in sleep… did not worsen by 18 months, despite more than double the amount of plaque burden,” Constantino said.

Also read: What Is Type 3 Diabetes? Insulin Resistance In The Brain That Could Trigger Alzheimer’s

Why Do Alzheimer’s Patients Lose Sleep?

Poor sleep and Alzheimer’s create a vicious cycle. Sleep deprivation reduces the brain’s ability to clear amyloid-beta and tau proteins, which can accelerate disease progression, while worsening sleep.

Sleep disturbances affect up to half of people living with Alzheimer’s disease. The disease disrupts sleep due to various reasons:

Overactive microglia: As shown in the new study, immune cells become chronically activated by amyloid plaques, releasing inflammatory signals that keep the brain in a heightened state of activity.

Damage to sleep-regulating brain regions: Alzheimer’s progressively affects areas like the hypothalamus and brainstem that regulate the sleep-wake cycle.

Loss of NREM sleep: Due to lack of deep sleep, the brain’s ability to clear metabolic waste, including amyloid plagues weakens.

Circadian rhythm disruption: Degeneration of the brain’s internal clock leads to broken sleep and daytime drowsiness. This fuels confusion and agitation associated with the disease.

Obesity has always been considered as one of the contributors to heart disease, diabetes, and stroke.

Now, growing research suggests that excess body fat, particularly in your 40s and 50s, may also accelerate brain aging and raise the risk of long-term cognitive decline.

Researchers say that obesity is not just linked with memory problems but also to significant changes in the brain structure.

Maintaining a healthy weight, especially during midlife, could help prevent memory problems and overall cognitive decline.

Higher BMI Linked To Faster Brain Aging

A recent study by researchers at the University of Georgia followed more than 8,200 adults aged 50 years and older for nearly 24 years.

The researchers found that individuals whose body mass index (BMI) increased over time experienced faster declines in cognitive performance than it would with normal aging. Excess body weight affected several aspects of cognition, including memory, planning, decision-making, problem-solving, emotional regulation, and concentration.

Lead author Dr. Claire Sexton (University of Georgia College of Public Health) said, "Maintaining a healthy body weight throughout adulthood may be an important strategy for preserving cognitive health later in life."

The study adds to the evidence that preventing weight gain throughout adulthood could become crucial for reducing dementia risk.

Also read: Grade-1 Fatty Liver: More Indians Are Developing It at Lower BMIs. What's Behind the Shift?

How Does Obesity Affect The Brain?

Chronic Inflammation

Obesity causes chronic low-grade inflammation, which can potentially damaging neurons essential for learning and memory.

Insulin Resistance

The brain relies on glucose for energy. Insulin resistance, common in obesity, may impair how brain cells use glucose, affecting memory and thinking.

Reduced Blood Flow

Obesity increases the risk of hypertension, atherosclerosis and vascular disease, reducing blood supply to brain tissue and potentially accelerating cognitive decline.

Visceral Fat

Experts believe visceral fat, the fat surrounding internal organs, may be more damaging than body weight alone. It produces inflammatory chemicals linked to brain changes and dementia risk.

Also read: Beyond Weight Loss: Scientists Discover How Exercise Can Help Reverse Muscle Aging

Growing Evidence

The latest findings are supported by several years of research. A large review published in Practical Neurology concluded that obesity is associated with smaller hippocampal volume, temporal lobe atrophy, mild cognitive impairment and increased Alzheimer's disease risk.

Some studies have suggested that obesity during midlife may nearly double the risk of developing Alzheimer's disease or dementia later in life.

Another review on obesity and aging reported that higher BMI is associated with poorer verbal memory, slower information processing and reduced executive function, particularly among older adults.

In January 2026, researchers also used genetic analyses to suggest that obesity and high blood pressure may directly contribute to dementia.

Can The Risk Be Reduced?

With a few lifestyle improvements, overweight and obese individuals can maintain a healthy BMI, reducing the risk of faster brain ageing and cognitive degradation. Experts recommend focusing on overall metabolic health rather than the number on the weighing scale alone.

Maintaining a healthy weight, regular exercise, controlling blood pressure, cholesterol and diabetes, following a Mediterranean diet, getting adequate sleep, remaining socially and mentally active can help maintain a healthy body weight.

Living with someone who has hepatitis can be worrying. People tend to immediately wonder whether they are at risk simply by sharing meals, hugging, or living under the same roof.

Fortunately, the answer depends on the type of hepatitis, and in most cases, everyday household contact does not spread the virus.

Dr. Shalimar, Prof. Department of Gastroenterology, AIIMS explains, "Hepatitis means inflammation of the liver. There can be many causes, but viral hepatitis is one of the most common. There are different hepatitis viruses, including A, B, C, D, and E. Some cause acute illness, while others can lead to long-term liver damage, including cirrhosis and liver cancer."

Experts say misinformation surrounding hepatitis often leads to unnecessary fear and stigma, causing patients to feel isolated. Understanding how different hepatitis viruses spread can help families protect themselves without avoiding normal interactions.

Can You Get Hepatitis By Living With Someone?

Dr Nanda Kishore M, Gastroenterology, Athulya Geriatric Care Hospital, answers our question, "No, Hepatitis is not a communicable disease that spreads through everyday contact such as hugging, holding hands, coughing, or sneezing."

For most forms of hepatitis, the answer is no. However, hepatitis B is spread through contact with infected blood and certain body fluids. Household transmission is possible, but it generally occurs when infected blood enters another person's bloodstream.

Possible household risks include sharing:

• Razors
• Toothbrushes
• Nail clippers
• Glucose monitoring devices
• Any item contaminated with blood

Also read: Can Hepatitis Be Completely Cured? Understanding What Treatment Can Achieve

Dr. Kishore says that the mode of transmission largely depends on the type of hepatitis infected.

He says, "Hepatitis A and E are predominantly spread via means of contaminated food and water, while Hepatitis B and C are transmitted through infected blood and certain bodily fluids."

Hepatitis B is preventable by vaccine. Household members of someone with chronic hepatitis B are usually advised to get tested and vaccinated if they are not already immune.

Dr. Shalimar says, "For hepatitis B, current treatment controls the infection, and newer therapies under development offer hope for a functional cure in the future. Vaccination has dramatically reduced hepatitis B in many parts of the world. Expanding vaccination coverage remains one of the most effective ways to prevent the disease."

Living with a hepatitis infected individual is generally safe given that basic hygiene and recommended precautions are followed strictly. Understanding these facts helps reduce unnecessary fear and stigma associated with it.

Also read: Grade-1 Fatty Liver: More Indians Are Developing It at Lower BMIs. What's Behind the Shift?

Importance of Screening & Prevention

Living with someone who has hepatitis does not mean you need to keep your distance. Instead, focus on practical precautions:

• Never share personal items that may come into contact with blood.
• Cover cuts and wounds.
• Wear disposable gloves while cleaning blood spills.
• Practice good hand hygiene.
• Ensure hepatitis B vaccination if recommended.
• Attend regular medical follow-ups if advised by your healthcare provider.

Dr. Ankur Jain, Associate Director & Unit Head, Gastroenterology, Hepatology & Endoscopy, Max Hospital, Dwarka, explains, "Hepatitis B and Hepatitis C continue to affect millions of people worldwide and remain major causes of liver cirrhosis and liver cancer. Individuals with a history of blood transfusions before routine screening, unsafe injections, or other risk factors should discuss screening with their physician.

He adds, "The liver has an extraordinary capacity to heal, but only if we identify problems early and address the underlying causes. Prevention, timely screening, and simple lifestyle modifications remain our most powerful tools in reducing the growing burden of liver disease in India."