Sleep deprivation has been linked to hypertension, obesity and diabetes and has long been suspected of having a connection to dementia. Now, a large new study has more clearly established that association by concluding that people who sleep less than six hours a night in midlife have a greater risk of developing late-onset dementia.
That doesn’t mean middle-aged short sleepers should panic, according to experts. Although the study is an important step forward, much about the connection between sleep and dementia remains unknown, they said. Still, it can’t hurt to work on your sleep habits while research continues, and you’ll find some strategies listed below.
In the study, European researchers followed nearly 8,000 people in Britain for 25 years, starting when subjects were 50. They found that those who consistently got six hours of sleep or less per night in their 50s and 60s were about 30 percent more likely to develop dementia later in life, compared to those who logged seven hours of sleep per night. That was independent of “sociodemographic, behavioural, cardiometabolic, and mental health factors,” the study authors wrote. Findings were published in the journal Nature Communications in late April.
“This is just another example of the importance of appropriate sleep for brain health,” said Michael V. Vitiello, a professor of psychiatry and behavioral sciences at the University of Washington at Seattle and member of the SleepFoundation.org medical advisory board, who wasn’t involved in the study. “It’s really important for people to be conscious of making sure that they sleep well. It’s not trivial, and it shouldn’t be the last thing you think about. It shouldn’t be the thing you sacrifice.”
Lack of sleep might increase dementia risk by impairing learning and memory development, said study author Andrew Sommerlad, an old-age psychiatrist at University College London, or it could affect the brain’s ability to clear harmful protein waste products.
Researchers have spent years trying to understand the sleep-dementia connection, a quest that becomes more urgent as the number of people with Alzheimer’s disease balloons. More than 6 million Americans are living with the disease, according to the Alzheimer’s Association, and by 2050, that number is expected to reach nearly 13 million. Yet, it’s a difficult area in which to draw conclusions.
Earlier this year, Charles Czeisler, chief of the sleep and circadian disorders division at Brigham and Women’s Hospital in Boston, co-authored a similar study that found that adults age 65 and older who got five hours or less of sleep per night had double the risk of dementia than those who clocked seven or eight hours per night. Results were published in the journal Aging.
“At this point, it’s too early to say that behavior X leads to Y,” Czeisler said. “But the association certainly reveals the importance of continuing to study the relationship.”
One of the challenges to studying the link between sleep and cognitive decline is that it’s difficult to determine what happens first: Is too little sleep a symptom of the brain changes that often begin decades before cognitive problems appear? Or does it cause those changes? So far, that’s still unclear, said Claire Sexton, director of scientific programs and outreach with the Alzheimer’s Association.
“There’s mounting evidence pointing toward the relationship between sleep and dementia,” she said. “But there are a lot of unanswered questions. There’s no one factor that would guarantee someone will develop dementia, and there’s no one factor that will guarantee someone won’t.”
Vitiello lauded the new study’s lengthy follow-up period and examination of people in their 50s (most similar research focuses on those 65 and older). But he emphasized that the findings estimate increased risk for the entire population, not for any one individual. “These are predictions,” he said. “On average, if you have this kind of disturbed sleep, your odds go up this percentage. It doesn’t mean that just because you’re a 55-year-old sleeping under six hours a night, you’re guaranteed to have an increased Alzheimer’s risk of 30 percent.”
Exactly why someone is a short sleeper — for example, if they have insomnia, hold multiple jobs that require odd hours or naturally need less sleep — likely plays a role in their unique risk, he added. The study didn’t account for those factors.
Study author Séverine Sabia, an epidemiologist at Inserm, the French public-health research center, acknowledged that her team’s findings only indicate an association between short sleep duration and dementia — not causation.
“Dementia is a multifactorial disease, which means that several factors are likely to influence its onset,” she said, including physical inactivity, smoking and social isolation. “Sleep duration is one of them, but even if a person has poor sleep, there are other important prevention measures.”
So, the takeaway for those with subpar snooze times? “No reason to panic,” Sabia said — pointing out that doing so might actually “worsen sleep quality,” but it’s a smart idea to work on getting better, and longer, sleep. Here are some strategies:
Be consistent. It’s best to wake up and go to bed at the same time every day on weekdays and weekends. Most importantly, “maintain your rise time, because that will partially set your going-to-bed time,” Vitiello said. He noted that there’s no need to force yourself into bed early, even if you have a special event the next day: “Biologically, your body is designed to sleep a certain amount, and if you extend your bedtime, it doesn’t guarantee you’re going to fill it with sleep.” You’ll likely toss and turn, wide-awake.
Make changes slowly. Like anything else, it can help to ease into healthy new habits. Jumping straight from, say, four hours of sleep a night to seven will be difficult for many people, Czeisler said. He recommends steadily increasing your sleep schedule by 15 or 20 minutes in the night and/or morning.
Develop a pre-sleep routine. Think of this as a ritual that helps you ease out of the day’s havoc and into a calm, sleep-inducing state. “You don’t want to just go directly from the evening news, and being depressed and anxious about it, to the bedroom,” Vitiello said. Different people will migrate toward different transitions — a book-lover might read, for example, though he recommends avoiding dramatic novels that could interfere with the ability to fall asleep. Others might take a warm bath or meditate.
Optimize your bedroom. Vitiello is based in Seattle — a high-latitude city that will soon experience light from around 4 a.m. to 10 p.m. So, if he were light sensitive, he’d install blackout curtains. Setting yourself up for optimal sleep also includes adjusting the room temperature to your liking, perhaps installing a white-noise machine and making your bed extra comfortable.
Cut back on artificial light. There are lots of tools that can help protect against exposure to blue light, which streams out of devices such as smartphones and computers and can disrupt sleep patterns. Various apps help to block blue light, and you can also dim the brightness on your phone.
Be mindful of lifestyle habits. Sleep is part of a healthy lifestyle, Vitiello said, along with following a healthy diet, getting enough exercise and paying attention to alcohol use. Alcohol might help you fall asleep more quickly, he said, but it can lead to a lower quality of snoozing. “I’m not saying you can’t drink a glass of wine before bed as part of your wind-down ritual, but if you feel your sleep is rocky in the second half of the night when you do that, then it’s not a good thing,” he said.
Prioritize it. Being aware of the importance of good sleep is often the most crucial factor to improving it — the key is not “being passive,” Vitiello said. And if you find you’re struggling to improve your slumber, or you don’t feel rested during the day? Talk to your doctor or set up an appointment at a sleep center. “Most sleep problems have a solution,” Vitiello said. “Not everything can be cured, but everybody with a problem can be helped.”
Do financial traders make better returns in the stock market when they are well rested? You would intuitively assume that a trader’s level of sleep would affect their decision making.
Several studies have certainly shown that sleep affects the ability of people to make decisions in general. Though admittedly based on small samples of participants, these studies show that those who are short on sleep tend to have relatively low attention to detail, poor memory, poor performance and significant mood swings.
But when it comes to whether sleep affects financial decisions, the evidence has been mixed. The only measure of sleepiness that has been used is the annual clock changes for daylight saving that take place in many countries, since they disturb many people’s sleep. A few studies have used this to look at how stock market returns are affected on the Mondays directly after the clocks go back or forward by an hour.
One such study in 2000 concluded that returns were relatively low when traders lacked sleep, and suggested that the lack of sleep might make them more risk-averse because they were anxious and struggling to concentrate. But later studies, such as this one from 2002, suggested that the correlation between sleep and cautious investing might not be as strong empirically as initially thought.
Daylight-saving time changes have the advantage that we all have to adjust them, but they are far from an ideal proxy for sleep since they only occur twice a year, and the impact on people’s sleep is relatively small since the clock only changes by an hour. This might explain why the research evidence has been mixed in this area.
To try and improve our understanding in this area, I undertook a pilot study of a fund manager in England, analysing his investment transactions in the context of sleep data that he recorded in a diary.
I found that his sleep patterns did indeed influence his investment decisions. In line with the theory from the 2000 study, the fund manager made fewer transactions when he was short on sleep.
To see whether there was a wider correlation, I sought to develop a new proxy for sleep. We know that around 80% of people search for information online about their health issues, and there is no reason to believe that investors behave any differently. I also knew that Google data has been used by researchers to measure investor attention to individual stocks.
I therefore created a sleepiness index based on the extent to which people in the US were searching Google for 28 relevant terms including “sleep deprivation”, “sleeping pills” and “jet lag cure”. Some of these terms came from allowing the Google algorithm to offer up potential sleepiness terms based on suggested autocompletes.
The more that people searched for things to do with sleepiness, the greater the indication of sleep difficulties. Unlike the time changes from daylight saving, my index has the advantage of being based on daily data, and can measure a much wider range of sleepiness. To test its validity, I checked the index against times that we would normally associate with sleepiness, including daylight-saving time changes and also sunrises and sunsets. Sure enough, sleepiness-related Google searches increase at these times.
The index confirmed that stock-market returns are indeed quite low on days that traders are short on sleep. For every 1% daily increase in sleep difficulties across the population, stock-market returns fell by 0.14%. I also found that these patterns reversed on subsequent days, which may mean that traders realise that their initial decisions were poor and take steps to correct them.
What next from a research point of view? Researchers could potentially use the data from sleep apps to get more accurate measures of the relationship between stock market returns and the population’s sleepiness over time. No doubt the better we understand this, the more that traders will be able to use it to their advantage.
My work is another example of how online search data can shed new light on old research subjects. There are surely lots of other ways in which the academic community can use it to understand other factors that influence our decisions.
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Time is something we all need more of, but how can you get more of it when there is only 24 hours in a day? Sadly there is no way to put more hours into each day, but what you can do is be more efficient with your time so you can follow your dreams. Here is how I was more efficient during my college years, which allowed me to run a business at the same time.
Watch television on the web – the problem with television is that you had to watch TV shows when they want you to watch them. Now with the technology advancements most entertainment channels like NBC, FOX, CW, and even a few cable networks let you watch your favorite TV shows online. It is free, you can watch the shows when you want to, and an hour show usually ends up being 45 minutes because there are a lot less commercials.
Sleep more – if you learn to take power naps, you will have more energy throughout the day. Although you may lose some time from napping, you will be able to work more efficiently, which will give you more time.
Eat healthy meals – changing your diet maybe hard at first, but eating balanced meals will affect how you do your daily tasks. It will give you more energy so you can get your work done faster.
Do less work – a lot of the things you do on a daily basis, don’t need to be done. Think about your daily routine and cut out anything that isn’t essential. You will be surprised on how much time you are wasting.
Tell people what’s on your mind – being honest and to the point is a great way to accomplish things quicker. When you beat around the bush things don’t get accomplished as fast. Just think about boardroom meetings, people are hesitant to say what is on their mind, which causes meetings to drag on forever.
Have some fun – all work and no play is a good way to make you feel depressed. Get some fun into your life, it will make you feel better, work harder, and hopefully make you want to accomplish your dreams.
Adjust your working hours – many companies are very flexible on what times you can start and end work. If you work in a heavy traffic city such as Los Angeles you can easily spend an hour or 2 commuting to work during rush hour. But if you adjust your working hours you can cut back on driving time drastically.
Cut down on your communication methods – cell phones, email, and instant messaging are just a few tools you probably use to communicate with others. The problem with some of these methods is that they can easily be abused. For example if you log onto AIM, you may waste an hour talking to others about junk. Try and use communication tools like AIM only when you need them.
Don’t multi-task – when you mult-task you tend to switch between what you should be doing and what you shouldn’t. By single tasking you are more likely to do what you are supposed to be doing.
Get rid of distractions – things you may not be thinking of can be distractions. Whether it is gadgets or even checking emails every 5 minutes, this can all distract you. By getting rid or distractions or controlling them, you will have more time on your hands.
Saving time creates time to focus on you and your goals. But finding time is only half the battle. You need to remain as productive as possible with the time you have to make the most of it.