How much humans sleep could be impacted in the coming decades due to climate change, a study in the Journal One Earth reported. 

The study found that by the end of the century, humans could average 58 fewer hours of sleep per year due to rising temperatures. The study found that people who sleep in warmer climates generally get less sleep.

“In real-world settings, humans appear to be better at adapting their surroundings to obtain sufficient sleep under cooler outside conditions, whereas sleep loss increases with rising ambient temperatures,” the study noted.

The elderly, women, and residents of lower-income countries are impacted most, the authors wrote.

“High ambient temperatures may predispose susceptible segments of society to worsened affect, anger and aggression, hypertension and adverse cardiovascular outcomes, diminished cognitive performance, elevated risk of accidents and injuries and compromised immune system functioning,” the study wrote.

Why do we sleep? Scientists try to answer the question

Updated: 11:42 PM EDT Jun 4, 2022

It’s strange when you think about it: Human beings spend nearly a third of their lives lying down with their eyes closed, dead to the world. But we have a biological need for sleep because it delivers numerous unbeatable benefits; it gives us more energy, reduces stress, and bolsters the immune system. While we sleep, our bodies also repair cells and fine-tune hormone levels.Related video above: Americans Want Better Sleep! Here Are Some Ways They’re Trying to Get That Done“Sleep affects almost every tissue in our bodies,” Dr. Michael Twery, a sleep expert, writes in a blog post for the National Institutes of Health. “It affects … our immune system, appetite, breathing, blood pressure, and cardiovascular health.” On the flipside, not sleeping enough can have disastrous consequences on our wellbeing. Drowsy people are much more likely to make poor decisions and be involved in traffic accidents. And chronic sleep deprivation can lead to a weakened immune system and increase your risk of developing depression.These are all compelling reasons to hit the sack, but they don’t completely explain why humans spend 8 hours unconscious and paralyzed each night. As noted sleep scientist Allan Rechtschaffen once said, “if sleep doesn’t serve some vital function, it is the biggest mistake evolution ever made.” For decades, scientists have been trying to solve the mystery of why humans sleep, with four possible theories paving the way: the inactivity theory, the energy conservation theory, the restorative theory, and the brain plasticity theory. Inactivity TheorySometimes referred to as the “adaptive” or “evolutionary” theory, the inactivity theory was one of scientists’ first stabs at an explanation behind sleep, made back in the 1920s, before scientists had started sleep labs or discovered rapid eye movement. The idea is that for animals, night is a vulnerable time, when darkness makes it difficult to move safely or avoid predators. Lying still and silent was a good way to avoid danger until morning. Through evolution, the theory posits, this strategy eventually morphed into what we now call sleep. The inactivity theory has one glaring problem, though: falling unconscious at night would have heightened vulnerability and made it nearly impossible to react to danger. Energy Conservation Theory This theory suggests that the primary function of sleep is to cut down on the amount of energy an animal needs and how much it uses. For most of us today, grabbing a snack is generally a simple task, but for ancient humans, finding food required a ton of time and effort. Sleeping through the night—a time when hunting was challenging and hazardous anyway—was a good strategy to conserve energy.This theory is backed up by research that shows when humans are asleep, their metabolism slows by approximately 10% (this figure is higher in other species). For example, both body temperature and caloric demands drop while we sleep. Many researchers consider the energy restoration theory to be part and parcel of the inactivity theory.Restorative TheoryAfter a long night of sleep, we often feel not just rested, but restored. Some scientists think that physical and cognitive restoration is actually why we sleep. The restorative theory has gained steam in recent years thanks to a slew of convincing animal and human studies. For instance, in Rechtschaffen’s experiments, carried out in the late 1980s, lab animals deprived entirely of sleep lost all immune function and died in a matter of weeks. Scientists have also discovered that most restorative functions—including muscle and tissue repair, protein synthesis, and the release of growth hormones—occur while humans sleep.Additionally, it appears sleep somehow boosts our immune system. A 2009 Carnegie Mellon University study showed that people who got seven or fewer hours of sleep each night were about three times more likely to become ill when exposed to the common cold than those who got 8 hours or more. But it’s not just your body that’s rejuvenated while you catch your Z’s. When you are awake, a chemical called adenosine accumulates in your brain. A byproduct of cellular activity, it’s adenosine that is thought to make us feel tired; as more builds up during the day, the more tired we become. During sleep, the body clears adenosine from the brain, allowing us to feel refreshed and alert when the alarm goes off.Brain Plasticity TheoryOne of the newest and most exciting theories about why we sleep is based on research that suggests sleep is correlated to changes in the structure and organization of the brain, a phenomenon known as brain plasticity. This theory, sometimes called the information consolidation theory, forwards the idea that during sleep, our brain sorts through the information we have acquired that day, throwing out data we don’t need and storing the rest in long-term memories. Several studies support this notion, demonstrating that sleep deprivation has a negative impact on our ability to learn and recall information.Scientists still aren’t exactly sure how sleep and memories are connected, though many researchers think that the brainwaves during different stages of sleep may be correlated with certain types of memories, such as memories that preserve facts and others that preserve procedures. The brain plasticity theory may explain why infants and young children, whose brains are still developing, need so much sleep. Infants, for example, spend up to 16 hours a day asleep, and much of that time is spent in REM sleep, the stage during which most dreams occur.Whether sleep transforms our brains or conserves precious calories, scientists are unlikely to discover one, indisputable reason behind sleep. In fact—while these theories may have distinct names and proponents—the reason why we sleep is likely a combination of these ideas, or quite simply, all of the above.

Drowsy driving, which experts say is just as dangerous as drunk driving, is to blame for more than 6,400 deaths in the U.S. each year.

New data released today shows many Americans know the risks, but they do it anyway. The National Sleep Foundation surveyed more than 1,000 drivers.

Over 60 percent said they drove a car when they were so tired they could barely keep their eyes open.

The foundation says this is dangerous for several reasons:

• Sleepiness slows reaction time
• Decreases awareness of your surroundings
• Impairs judgment
• Increases risk of crashing.

"It's important to think about drowsy driving as impaired driving,” said Natalie Dautovich with the National Sleep Foundation. “Just like drunk, drugged or distracted driving, drowsy driving is a real public health issue."

She says drowsy driving is also an equity issue. She says people of historically underserved populations reported higher rates of drowsy driving.

"We know there's an occupation risk to drowsing driving, so if you're working extended shifts, if you're working rotating shifts or night shifts, you're at greater risks for driving drowsy," Dautovich said. "We know that historically marginalized individuals are more likely to have some of those occupational hazards."

She says the most important thing you can do is try to get enough sleep before getting behind the wheel. The National Sleep Foundation recommends adults get 7-9 hours of sleep a night.

Video above: Sleep specialist explains what lawmakers got wrong with permanent daylight saving time bill

The end of daylight saving time is upon us again, an autumn tradition when the United States, Europe, most of Canada and a number of other countries move their clocks backwards an hour in a sort of Groundhog Day trust fall. We'll move them forward (again) next spring when governments put daylight saving back in place.

But are we putting our trust in an unhealthy, outdated idea?

Not according to the United States Senate, which in March passed the Sunshine Protection Act of 2021 -- if it becomes law, daylight saving time will be permanent.

"The call to end the antiquated practice of clock changing is gaining momentum throughout the nation," said Senator Marco Rubio (R-FL), who first introduced the bill in the U.S. Senate, in a statement. Florida's legislature voted to make daylight saving time permanent in Florida in 2018, but it can't go into effect until it is federal law as well.

The bill still has to make its way through the U.S. House of Representatives and be signed into law by the president. If or when that is the case, we'll move our clocks forward and leave them that way, permanently living one hour ahead of the sun.

However, a growing number of sleep experts say the act of moving our clocks forward in the spring is ruining our health. Studies over the last 25 years have shown the one-hour change disrupts body rhythms tuned to Earth's rotation, adding fuel to the debate over whether having daylight saving time in any form is a good idea.

"I'm one of the many sleep experts that knows it's a bad idea," said Dr. Elizabeth Klerman, a professor of neurology in the division of sleep medicine at Harvard Medical School.

"Your body clock stays with (natural) light, not with the clock on your wall," Klerman said. "And there's no evidence that your body fully shifts to the new time."

Dr. Phyllis Zee, director of the Center for Circadian and Sleep Medicine at Northwestern University's Feinberg School of Medicine in Evanston, Illinois, also opposes daylight saving time.

"Between March and November your body gets less morning light and more evening light, which can throw off your circadian rhythm," she said.

Standard time, which we enter when we move our clocks back in the fall, is much closer to the sun's day and night cycle, Zee said. This cycle has set our circadian rhythm, or body clock, for centuries.

Video below: As clocks 'fall back,' here's where Mass. residents stand on daylight saving time

That internal timer controls not just when you sleep, but also when you want to eat, exercise or work, as well as "your blood pressure, your heart rate and your cortisol rhythm," Zee added.

A call to ban daylight saving time for good has come from the American Academy of Sleep Medicine: "Current evidence best supports the adoption of year-round standard time, which aligns best with human circadian biology and provides distinct benefits for public health and safety."

The proposal has been endorsed by more than 20 medical, scientific, and civic organizations, including the American College of Occupational and Environmental Medicine, the National Parent Teacher Association, the National Safety Council, the Society for Research on Biological Rhythms and the World Sleep Society.

What's the harm?

When our internal clocks are offset from the solar day-night cycle by even one hour we develop what sleep experts call "social jet lag." Studies have shown social jet lag increases the risk of metabolic disorders such as diabetes, raises the risk of heart disease and stroke, worsens mood disorders such as depression, affects the digestive and endocrine systems and shortens our sleep duration. It can even reduce life expectancy,

A 2003 study found getting one hour less sleep for two weeks had the same effect on thinking and motor skills as going without sleep for two full nights. Reducing sleep by 90 minutes from the recommended 7 to 8 hours for adults altered the DNA of immune cells and boosted inflammation, a key cause of chronic disease, according to another study.

Making the time change permanent would make the chronic effects of any sleep loss more severe, not only "because we have to go to work an hour earlier for an additional 5 months every year but also because body clocks are usually later in winter than in summer with reference to the sun clock," according to a statement from the Society for Research on Biological Rhythms.

"The combination of DST and winter would therefore make the differences between body clocks and the social clock even worse and would negatively affect our health even more," the authors concluded.

Video below: Permanent daylight saving time would reduce deer crashes, study says

Why did the Senate pass the bill?

There are reasons the U.S. Senate unanimously passed the Sunshine Protection Act. Proponents say that extra daylight in the evening cuts down on car accidents and crime, and increases opportunities for commerce and recreation, as people prefer to shop and exercise during daylight hours.

However, research has shown both heart attacks and fatal car accidents increase after the clock falls forward in the spring. Children also end up going to school in the morning while it is still dark -- with disastrous consequences.

When President Richard Nixon signed a permanent daylight saving time into law in January 1974, it was a popular move. But by the end of the month, Florida's governor had called for the law's repeal after eight schoolchildren were hit by cars in the dark. Schools across the country delayed start times until the sun came up.

Video below: Sleep specialist explains what lawmakers got wrong with permanent daylight saving time bill

By summer, public approval had plummeted, and in early October Congress voted to switch back to standard time.

A similar backlash occurred when the U.S. first implemented daylight saving time in 1918, as a way to reduce demand for electricity usage by adding sunlight to the end of the day in response to World War I. (Studies since have found little to no cost savings from the practice.) The time switch was so unpopular that the law was repealed the following year.

"The United States has tried permanent daylight saving time twice before and ended it early. The UK tried once before and ended it early. Russia tried it once, so did India and ended it early," Klerman said. "I think we should learn from history."

What's the purpose of sleep? Doctors emphasize importance of sleep, say we're not getting enough

Updated: 8:07 PM EST Feb 13, 2023

How much sleep did you get last night? For many Americans, that answer is, "Not enough."We've all heard the quip, "I'll sleep when I'm dead," joking about not getting enough rest.But sleep experts in Baltimore told sister station WBAL it's really nothing to joke about: Sleep is vitally important to the health of our bodies and our brains.Everything sleeps. But why? It's a question that Johns Hopkins Medicine neurology professor and sleep researcher Dr. Mark Wu has spent his career working to answer."Every animal sleeps, ranging from your cat, your dog at home, but even tiny little fruit flies we study in the lab, they also sleep. So, what is it for?" Wu said.There are two things about sleep for which Wu is sure."Clearly, it's something important," Wu said. "It's clear that Americans are not sleeping enough, they're not getting enough good, quality sleep, and it's bad for their health."| RELATED: You're probably not getting enough sleep. Here's what experts suggest.This is a relatively new problem. According to the National Sleep Foundation, average Americans slept eight to nine hours a night in the 1950s. By the 2000s, that number dropped to a little more than six hours. There's a reason coffee houses are popular in our culture."It feels to me, the culture is work, work, work, and if you sleep, you're somehow weaker," said Kim Scarfe, a new mom.Not all sleep is the sameWhat happens to a person's body in the hours of unconsciousness is vital. Dr. Raya Wehbeh, a sleep doctor at the Greater Baltimore Medical Center, explains."Restoration of body tissues, memory consolidation, getting rid of waste, strengthening of immunity. In general, the mood is much better when you get enough sleep. There's a lot that happens during sleep," Wehbeh said.There are different stages of sleep: As you drift off, first comes light sleep. About 20 minutes later, you enter deep sleep, which is critical because slow brain waves wash out waste that cells make."Just imagine hundreds of billions of neurons in your brain undergoing these slow waves, and then there's another stage of sleep we undergo called REM sleep -- or rapid eye movement sleep, the period of sleep when we're dreaming vivid dreams, like in a movie -- and our bodies are paralyzed," Wu said.| RELATED: Surprising sleep hacks that actually workWe're paralyzed except for our eyes, hence the name "rapid eye movement."When measuring REM brainwaves, they look remarkably like brainwaves of someone awake. If you think you don't dream, you do. Everyone does. You just don't remember.This cycle of light sleep, deep sleep, then REM sleep repeats itself several times a night."But one of the things that's a little but interesting is that the first third of your night is mostly comprised of slow wave, or deep sleep, and the last third of your night has more of the REM sleep, which is why, sometimes, you might find that early in the morning, you tend to remember your dreams better," Wu said.How much sleep is enough?Experts recommend seven hours of sleep for many people, but some need 10 while others only need six. Pay attention to how you feel. And, when you sleep is important, too."Even if you slept eight hours from 6 p.m. to 2 a.m., you are not going to feel rested because you're sleeping at the wrong time," Wu said.| RELATED: Tips on adjusting your sleep schedule after Daylight Saving TimeBoth Weybeh and Wu said the consequences of not getting enough sleep at the proper time can be serious and can include:Slowed metabolism, causing weight gainWeakened immune systemWorsened brain conditions, like migraines and epilepsyDiminished concentration, learning and memory"If you don't get enough sleep, it's bad for overall brain health, like accumulation of toxic proteins in your brain that may lead to Alzheimer's disease," Wu said. "I think we really have to look at sleep as one of the three pillars of human health. We talk a lot about diet. We talk a lot about exercise. We really need to think about sleep as the other part that we need to take care of to optimize our health, not only our bodies but our brains as well."Scarfe agrees. For her, sleep is woefully hit or miss."On the days I'm not getting enough sleep, everything sucks. I can't do anything. I'm a terrible person. Then, I stop myself and think, 'Did you get sleep last night?' And, I'm like, 'Ohhh, no. I didn't,'" Scarfe said.In Part 2, we explore some of the more common, and more unusual, sleep disorders. Watch for that report Tuesday on 11 News at 4 p.m.| ALSO: Using melatonin for sleep is on the rise, study finds

Lifting more weights could work wonders for your sleep quality, new study suggests

Updated: 9:07 AM EST Jan 2, 2021

It’s all too easy to get stuck in a cycle of not being able to fall asleep at night — or struggling to stay asleep — and then feeling groggy the next morning. In fact, 1 in 4 Americans experience insomnia each year and 70 million Americans suffer from some sort of sleep disorder. So, if you’re struggling with sleep issues, you’re definitely not alone. However, the takeaway from a new study in Preventive Medicine Reports says that adding some strength training into your routine during the day can actually help improve your quality of sleep. Researchers looked at over 23,000 adults in Germany, collecting data on their weekly frequency of resistance exercise and sleep quality. They found that any muscle-strengthening done during a typical week was associated with a reduced prevalence of sleep rated as “poor” or “very poor.” These associations remained after adjusting for other factors like high body mass index, chronic disease, age, and smoking.Also, there was no evidence of a dose-dependent relationship, which means more was not necessarily better. Those who did resistance training just once a week had a similar, favorable association in sleep quality to those who did this type of training more often, even those who strength-trained five times a week.“There is strong scientific evidence that exercise is associated with better sleep quality, but most of that evidence is based solely on aerobic exercise,” lead study author Jason Bennie, Ph.D., associate professor in physical activity epidemiology at University of Southern Queensland in Australia, said. “Our study was the first to describe the associations between muscle-strengthening exercise and sleep quality, especially among a large population sample.” One limitation to the study is that the study’s results were based on participants self-reporting the amount of strength training they did, which is much less precise than direct observation. But even if participants in this research were overestimating, the fact is that resistance training on a regular basis still helps in a breadth of ways, including helping you get more, better sleep, according to W. Chris Winter, M.D., president of Charlottesville Neurology and Sleep Medicine, and author of The Sleep Solution. “Compared to lighter exercise like a leisurely run, strength training tends to create a bigger surge of adenosine,” he said.Adenosine is a molecule that, when broken down during the digestive process, becomes adenosine triphosphate, or ATP, which is responsible for intercellular energy exchange. When ATP is naturally depleted through activity, it breaks back down into adenosine and at that point, tends to cause drowsiness. Having a larger amount of adenosine through strength training can streamline this process and create more of a drive to sleep, said Winter.Other potential explanations, said Bennie, are enhanced glucose and lipid metabolism, reduced high blood pressure, and fewer symptoms of anxiety and depression — which all are likely to be beneficial for sleep quality. “The bottom line is that exercise impacts sleep, and this study is good reinforcement of that message,” Winter said.