Experiencing daytime sleepiness is something that is usually perceived as a minor inconvenience, but for older adults, it could be an early warning sign of Dementia. This neurodegenerative disease leads to the progressive decline of brain cells. This eventually

affects memory, cognition, and personality, making everyday tasks more difficult. As one of the fastest-growing neurological disorders across the world, dementia poses a significant health threat to ageing populations.

Is Dementia Linked To Poor Sleep?

For this study, researchers followed 445 older adults (average age 76) over three years, aiming to determine whether poor sleep could increase the risk of mild cognitive impairment (MCI), which often leads to dementia. At the start, none of the participants had MCI, but by the end of the study, 36 individuals had developed the condition.

The researchers discovered that participants with poor sleep were more likely to develop MCI compared to those who slept well. However, when depression symptoms were taken into account, the link between poor sleep and MCI became less pronounced, suggesting that while sleep issues are a concern, mental health also plays a key role in dementia risk.

To assess sleep quality, the Pittsburgh Sleep Quality Index (PSQI) was used, evaluating factors such as sleep duration, disturbances, and daytime alertness. Among these, "daytime dysfunction"—defined as excessive sleepiness and low energy during the day—was most strongly associated with an increased risk of MCI. Those experiencing daytime dysfunction were more than three times as likely to develop MCI as those who didn’t report such symptoms.

There are many types of dementia:

Dementia is not a specific disease. According to the Centers for Disease Control and Prevention (CDC), it is an overall term that describes a decline in mental ability that interferes with daily life. People with dementia often have symptoms like trouble remembering, thinking, or making everyday decisions. These symptoms tend to get worse over time.

Alzheimer’s disease is the most common type of dementia, and it mostly affects the elderly. Each form of dementia has a different cause. Though dementia mostly affects older adults, it is not a part of normal ageing. An estimated 6.7 million older adults have Alzheimer's disease in the United States. That number is expected to double by 2060, as per data from the CDC.

In 2022, 3.8% of men and 4.2% women in US were diagnosed with dementia. The percentage of people increase with age from 1.7% for those aged 65-74 to 13.1% for those aged 85 and older. Alzheimer's accounts for 60 to 80% of all dementia cases and it is most prevalent in California, Florida, and Texas, as these states have the highest number of people.

The ongoing outbreak of hantavirus, a rodent-borne disease, among passengers aboard the luxury cruise ship MV Hondius has been linked to climate change, according to health experts.

So far, the outbreak has affected only people connected to the cruise ship, with eight reported cases, including three deaths. Six cases have been confirmed to be caused by the Andes strain of hantavirus.

The disease is expected to result in more cases as public health officials across 12 countries — including the United States, United Kingdom, Spain, and the Netherlands — continue contact tracing and screening efforts. In addition, the disease’s incubation period, which can last several weeks, may make screening more difficult.

According to the World Health Organization, an elderly Dutch couple may have brought the virus aboard after possibly contracting it through rodent exposure during a bird-watching tour near a landfill in Ushuaia, days before the ship departed from Argentina. Both the husband and wife later died.

Hantavirus Outbreak: Why It May be Linked To Climate Change

Experts have blamed climate change and habitat destruction for the rise in cases of the disease, which is usually caused by exposure to the urine or feces of infected rodents.

Rising temperatures, changing rainfall patterns, and habitat destruction are driving rodents closer to human populations, increasing the risk of hantavirus transmission through contaminated urine, droppings, or saliva.

“Climate change and rodents are closely linked, particularly because global warming creates conditions that favor the spread and survival of many rodent species, including rats. Rising temperatures make previously colder regions more suitable for rodents, allowing them to expand their geographical range into areas where they were once less common,” said Dr. Rajeev Jayadevan, convenor of the IMA research cell, in a statement to HealthandMe.

In general, colder regions tend to have fewer rats, but warming temperatures are changing that pattern.

“Increasing human interaction with wild environments, habitat destruction, the establishment of small urbanizations in rural areas, and the effects of climate change contribute to the appearance of cases outside historically endemic areas,” Argentina’s health ministry said in a statement.

Dr. Jayadevan added that higher temperatures can also make rodent reproductive cycles more efficient.

“Since rodents are mammals, warmer weather may allow them to reproduce more frequently within a year, leading to larger populations over time. Even a small increase in reproductive cycles can significantly boost rodent numbers on a community scale, especially when food supplies are abundant,” he said.

Also read: Hantavirus: Israel Confirms 1st Case as UK, Spain Probe Suspected Infections; Should You Be Worried?

Hantavirus: Flooding and Urbanization Raising Risks

Climate change also contributes to extreme weather events such as flooding, which can further increase human-rodent interaction.

Notably, floods may destroy crops and disrupt natural food sources, forcing rodents to migrate into homes and urban areas in search of food and shelter. This closer contact between humans and rodents can increase the risk of rodent-borne diseases spreading.

Dr. Ishwar Gilada, an infectious disease expert based in Mumbai, said that climate change, flooding, overcrowding, poor sanitation, rapid urbanization, and ecological disruption can all increase the risk of zoonotic infections, including hantavirus.

“Floods and heavy rainfall often force rodents into human settlements, while garbage accumulation, slums, warehouses, and poorly planned urban growth create ideal conditions for rodent breeding and human exposure,” Dr. Gilada said.

These conditions increase the likelihood of contact with contaminated urine or droppings.

Read More: Donald Trump Says Hantavirus Is 'Under Control'; Questions Grow Over CDC Research Cuts

‘One Health’ Approach Key to Future Preparedness

Dr. Gilada also highlighted the growing importance of the “One Health” approach, which recognizes the close connection between human, animal, and environmental health.

“Although hantavirus remains uncommon in India and is not currently considered a major public health threat, the broader lesson is the importance of long-term preparedness through improved sanitation, rodent control, environmental management, and stronger disease surveillance systems,” he said.

The MV Hondius cruise ship, hit by an outbreak of hantavirus, is expected to reach the Canary Islands on May 10.

The vessel is set to dock near Tenerife, where residents have voiced concerns that its arrival could pose a potential health risk.

The Spanish government, in coordination with the World Health Organization (WHO), has agreed to allow passengers to disembark in the Canary Islands this weekend. The ship had travelled from Cape Verde, where three people were evacuated earlier due to illness.

According to the WHO, none of the passengers currently on board are showing symptoms of hantavirus.

Spain Issues Quarantine Measures

Despite the absence of symptoms among current passengers, Spain’s Health Ministry has announced strict quarantine protocols.

“All people considered contacts — those who remained on the ship between April 1 and May 10, or were in contact with a confirmed case — must undergo mandatory quarantine at the Central Hospital of the Gómez Ulla Defense in Madrid,” the ministry said.

Passengers will remain in individual rooms with no visitors allowed.

“During this period, they will undergo a PCR test upon arrival and another seven days later,” the ministry added.

Authorities will also carry out active surveillance, including twice-daily temperature checks to identify symptoms early.

If a laboratory test is positive by the National Microbiology Center, the patient will become a confirmed case and will be admitted to a High Level Isolation and Treatment Unit (UATAN) until clinical recovery.

WHO, CDC, ECDC Teams Monitoring Arrivals

According to media reports, more than 90 people from 23 nationalities remain aboard the Dutch-flagged MV Hondius. This includes: 38 Filipinos, 23 Britons, 17 Americans, 2 Indians and 14 Spaniards.

The 14 Spanish passengers will be transferred to Gómez Ulla Hospital in Madrid, where they will undergo a 45-day quarantine. Crew members from other countries will be repatriated to their respective nations.

WHO said it has developed and shared technical guidance documents in support of countries affected by the event, including covering management of the event on the ship, investigation of cases, disembarkation and management of returning passengers and crew members.

In its latest briefing, the UN health body said emergency response teams, including experts from the Netherlands and the European Centre for Disease Prevention and Control (ECDC), are coordinating efforts to manage the situation and assess all passengers and crew upon arrival.

A WHO official is currently on board alongside two Dutch healthcare workers and an ECDC expert.

WHO Technical Officer Anais Legand said health teams will review the exposure history of every passenger and crew member to determine who may face a higher risk of infection.

Passengers will also be screened for symptoms such as fever, fatigue, or signs of illness.

The US Centers for Disease Control and Prevention (CDC) said it plans to evacuate American passengers aboard the ship on a US government medical repatriation flight to Omaha, Nebraska.

Confirmed Andes Virus Cases

The WHO confirmed that six cases have tested positive for Andes virus, which can spread from person to person, through PCR testing.

The ship had 147 passengers and crew members on board when the outbreak was first reported on May 2, while another 34 people had already left the vessel.

Also read: Hantavirus: Israel Confirms 1st Case as UK, Spain Probe Suspected Infections; Should You Be Worried?

Four patients remain hospitalized in South Africa, the Netherlands, and Switzerland. A suspected case transferred to Germany later tested negative.

Contact Tracing Underway

Health authorities said contact tracing efforts will focus on identifying and assessing everyone who may have been exposed on board, particularly those who had close contact with confirmed or suspected cases.

Officials are evaluating several factors, including the incubation period, infectious stage of the virus, and overall risk profiles.

“You want to understand whether this person might be more likely to be sick,” Legand explained. Currently, there is no treatment or vaccine available for hantavirus.

What Is Hantavirus?

Read More: WHO Says 6-Week Hantavirus Incubation Raises Concern, But No Epidemic Risk

Hantavirus is primarily transmitted through contact with infected rodents or exposure to their urine, droppings, and saliva, though rare cases of person-to-person transmission have also been reported.

While hantavirus carries a mortality rate of up to 40 percent, the WHO stated that the overall global risk remains low.

According to the CDC, symptoms can appear one to eight weeks after exposure, initially presenting fatigue, fever, and muscle aches. As the disease progresses, it can cause coughing, shortness of breath, and chest tightness as fluid accumulates in the lungs.

A deadly case of hantavirus has been confirmed in Israel, while health authorities in the UK and Spain are investigating suspected infections in three individuals, raising fresh concerns over the spread of the rare rat-borne disease.

Hantavirus is primarily transmitted through contact with infected rodents or exposure to their urine, droppings, and saliva, though rare cases of person-to-person transmission have also been reported.

According to the World Health Organization (WHO), eight cases — including three deaths — have been confirmed so far. However, additional suspected and confirmed cases are continuing to emerge across countries.

Despite growing concern, the WHO, the US Centers for Disease Control and Prevention (CDC), and other health agencies have stated that the overall public health risk remains low.

Here’s a look at the countries reporting confirmed and suspected hantavirus cases.

Israel

The case in Israel, reported by the local newspaper Maariv, is believed to have been infected during a stay in Eastern Europe several months ago. It is reportedly not linked to the ongoing outbreak linked to the MV Hondius cruise ship in the Atlantic Ocean.

The patient underwent an antibody test after the symptoms appeared, which showed exposure to hantavirus, the report said. A PCR (polymerase chain reaction) test was then conducted to detect the virus’s genetic material, confirming the infection, it added.

The patient was said to be in stable condition, not in need of intensive care or strict isolation, and was being kept under medical observation.

Details about the patient and the medical center where the diagnosis was made could not yet be published, but have been reported to the country's Health Ministry.

UK

The UK Health Security Agency had confirmed two British cases connected to the outbreak on board the MV Hondius.

One remains in a stable condition in the Netherlands after being evacuated from the ship, the other remains in intensive care after being flown to South Africa last month.

A third case is also being suspected on the remote South Atlantic island of Tristan da Cunha, where the ship stopped in mid-April, the UK HSA said.

In addition, the agency said that two British nationals are self-isolating at home after potential exposure to hantavirus on the cruise ship. The pair had disembarked earlier in the voyage and currently shows no symptoms.

They were part of a group of 30 people from a dozen nations - including seven Britons - who disembarked from the ship at St Helena in the south Atlantic on 24 April, according to operator Oceanwide Expeditions. Four Britons who disembarked on St Helena remain there, BBC reported.

They do not have symptoms but are in contact with health officials. It is understood that medical staff will be sent to the islands to provide support.

Also read: Donald Trump Says Hantavirus Is 'Under Control'; Questions Grow Over CDC Research Cuts

Spain

A 32-year-old woman who shared an airplane with a MV Hondius cruise ship passenger who later died of hantavirus is now showing symptoms consistent with the disease, Secretary of State for Health Javier Padilla said while speaking to the media.

The woman ⁠has been taken to a hospital in Alicante, where she ⁠remains in isolation, he added. Her symptoms included coughing and "general malaise".

She is being transferred to a hospital in the city of Alicante where she will be tested ‌for ⁠the virus, with results expected 24 to 48 hours later, according to a statement on the regional health department's website.

Padilla said the woman, a resident of Alicante in the Valencia region, ⁠was sitting two rows behind the cruise ship passenger, but the contact between them "was brief" since the passenger had only been "on ⁠board for a short time" during the flight.

Netherlands

The World Health Organization confirmed that a KLM flight attendant, who was isolating in an Amsterdam hospital with mild symptoms after being in brief contact with a hantavirus patient, has tested negative for the virus.

Her case supports the WHO experts’ theory that the rat-borne disease can only be transmitted person-to-person through prolonged, close contact.

Singapore

Two Singaporean residents who were onboard the MV Hondius cruise ship have tested negative for the virus, the Communicable Diseases Agency (CDA) said today.

The 67-year-old and a 65-year-old had been tested and isolated in the city state. The CDA's National Public Health Laboratory conducted testing on multiple samples collected from the individuals and confirmed that hantavirus, including the Andes virus, was not detected, it said.

“The risk to the general public in Singapore is currently low,” the CDA said.

Hantavirus: The Common Symptoms And How To Reduce Your Risk

According to the CDC, symptoms can appear one to eight weeks after exposure, initially presenting fatigue, fever, and muscle aches. As the disease progresses, it can cause coughing, shortness of breath, and chest tightness as fluid accumulates in the lungs.

The CDC reports that about one-third of individuals who develop respiratory symptoms from the disease may not survive.

You can reduce your risk by eliminating and minimizing your contact with rodents in your home, workplace, or campsite. The best way is to seal holes and gaps in your home or garage and keep the rodents from entering your home. You can also place traps in and around your home to decrease rodent infestation. Clean up any easy-to-get food that could attract rodents.