If worrisome thoughts keep you up at night, many experts say you should add sleep debt to your list of woes.
According to the U.S. Centers for Disease Control, people suffering from sleep debt (which means less than seven hours of sleep a night for adults) have a greater risk of obesity, cardiovascular disease, diabetes, and other chronic health problems.
However, according to Jim Horne, a sleep neuroscientist and professor emeritus of psychophysiology at Loughborough University in the U.K., the evidence for this isn’t all that strong, and the message may actually do more harm than good.
“People with insomnia worry enough as it is when they’re trying to go to sleep,” said Horne, “and the risk of obesity and cardiovascular diseases are not particularly [high].”
In his new book, “Sleeplessness: Assessing Sleep Need in Society Today,” Horne examines the latest sleep research and historical evidence to challenge some prevailing notions about sleep.
For example, some blame the so-called sleep debt epidemic on an overworked, overstimulated society that forces us to function on less sleep than we need. But Horne points to evidence that the amount of sleep modern people get isn’t that different from in the past.
Epoch Times spoke to Horne about the function of sleep, how we benefit from better quality sleep, and the mechanics of dreams.
Epoch Times: What function does sleep serve?
Dr. Jim Horne: It serves a variety of functions. For humans, sleep is really something by the brain, for the brain. The cortex–the highest centers of your brain–is always active, it can never shut down. It’s in a state of quiet readiness.
Every other organ can actually rest and recover in relaxed wakefulness, but the cortex can’t do this. If you were to lie in bed at night and we measured the activity of all organs in the body, the only way that we could tell if you’re really asleep and undergoing considerable changes and recovery is by looking at the cortex.
For us, sleep really doesn’t conserve much energy compared to the great benefits it gives our advanced cortex.
Epoch Times: Your book discusses this issue of sleep debt, which we see in various studies in recent years. You suggest these claims of sleep debt in modern society may be overstated. How so?
Dr. Horne: A lot of attention is paid to sleep debt, but as far as we can tell, it is no greater today than it was 150 years ago. If you look at the medical journals of 150 years ago, you’ll see that people were complaining about not getting enough sleep, and they blamed the hustle and bustle of the industrial age. Trying to get people to get more sleep then was just as unproductive as it is today.
I’m not decrying sleep debt. But human nature being what it is, you have to sacrifice some aspects of wakefulness.
The reason many people have insomnia is because their mind is racing. The things in their waking life are intruding into their sleep. For people who suffer from insomnia, the idea that if they don’t get more sleep they’re liable to suffer from obesity, cardiovascular disease, or whatever, can perhaps be a greater worry than really is necessary.
The biggest risk for people who are not getting enough sleep is being sleepy during the day, and the consequence is having an accident as a result of the sleepiness.
One of the most important factors to improve one’s sleep is peace of mind at bedtime.
Epoch Times: How much sleep do we need?
Dr. Horne: There are individual differences and natural variation around sleep.
In the United States, over the last hundred years, the average amount of sleep people get is about seven hours a night. That really hasn’t changed very much.
But you can’t really judge sleep on its duration, because quality of sleep is just as important. For example, six hours of good quality sleep is far better than 10 hours of poor or interrupted sleep.
Epoch Times: How much do our sleeping habits differ from our ancestors?
Dr. Horne: Historically, in Europe and North America, people would have two sleeps. They would go to sleep in the evening for two to three hours, then wake up around one or two in the morning. They would get up, say their prayers, have something to eat, check that the house was safe, stoke the fire, and tend to the animals, etc. It was quite common for people to be awake for an hour or so, and then go back to bed for a second sleep.
An unbroken seven hours of sleep a night is probably more associated with the industrial age. Electric lighting has affected our body clock to some extent, and our perception of safety. A lot of evidence suggests that our striving for seven or eight hours of unbroken sleep at night is probably fairly recent in our history.
Epoch Times: Is there any advantage to splitting our sleep?
Dr. Horne: Interestingly, one of the most common forms of insomnia is to wake up in the middle of the night for an hour or so and then not be able to fall back asleep. One wonders whether this is a throwback to older times.
We all have a dip in energy in the early afternoon because we’re probably naturally designed to have two sleeps a day: one big one at night and another one in the early to mid-afternoon. A nap in the afternoon can be beneficial for many people.
Epoch Times: We often hear concerns about not getting enough sleep, but can we take more than we need?
Dr. Horne: One of the important things to consider is that one can sleep for pleasure, as well as for need. Like any biological function, you can indulge in it, in the same way we take more food or liquid than we require. It’s not simply to get rid of hunger or thirst, but for pleasure.
Epoch Times: Do you have any insights about dreams? What function do they serve?
Dr. Horne: Dreaming is something we don’t understand enough. I don’t think dreams resolve one’s inner worries and conflicts as Freud suggested. But he was right in that dreams are what we think. Dreams are a mixture of what you’re thinking, doing, and what’s on your mind during wakefulness.
Dreams happen during REM sleep. REM sleep generates internal stimulation to keep you asleep, but it is also keeping your ears open to listen for danger so you can wake up if necessary.
You can think of your brain like a computer. If you awaken during deep sleep in the middle of the night, it takes time for the brain to boot up. Whereas REM sleep is more like the screensaver mode.
We dream about four times a night, for a total of about an hour and a half. We often have no recollection of these dreams unless we awaken quickly, but we can generally only recall the last few minutes.
Most dreaming occurs toward the end of the night. The body gets all the vital processes done at the beginning, and as sleep progresses, it gets less and less vital. So whatever is more loaded toward the end of sleep, such as dreaming, is less important or essential.
Dreams are quite a phenomenon, but I think the only person who can interpret dreams is the dreamer himself. Someone else—who doesn’t know what you’ve been up to, what you’ve been thinking and doing, and what’s been on your mind—is going to have great difficulty understanding what it means.
Epoch Times: So if you dream of a mushroom, for example, this doesn’t universally symbolize the same thing for everybody?
Dr. Horne: Right, some people may dream of mushrooms because they enjoy mushroom soup. Other people might associate mushrooms with a nuclear cloud.
Epoch Times: What direction would you like to see sleep research take?
Dr. Horne: I think sleep researchers spend too much time understanding sleep solely from a laboratory. Sleep is more flexible than we tend to think. Perhaps we should link up with sociologists and historians, and get a wider understanding of sleep from an environmental perspective of everyday life.
The reason we sleep is to avoid sleepiness in the daytime. But we need to think more broadly in our understanding of sleep beyond just alleviating sleepiness. How does sleep affect our cognitive function and our ability to think creatively? These are things that are difficult to measure.
The problem is that it’s easy to measure sleepiness, and we are attracted to the technology. But perhaps we should step back a bit, and not be driven so much by things that are easy to measure.
Answers have been edited for clarity and brevity.