What You Don’t Know About Sleep
Send us your questions for Dr. J.
March 1st, 2013
Question: Why do some people need more sleep than others?
The long and the short of it
Our sleep question of the month comes from Penny who asks “Why do some people need more sleep than others?”
Well Penny, that is a great question. First of all, you have astutely discounted the common fallacy (propagated by grandmothers everywhere), that everyone should get 8 hours of sleep per night.
In truth, sleep need is distributed along a bell curve. On the extremes are people who need as few as 3 or as many as 11 hours of sleep each night. Eight hours (actually 7.5) is only what the average person needs.
Scientists who study this type of thing call those who need 6 hours or less “short sleepers” while “long sleepers” are defined as those who need 10 hours or more.
Thomas Edison was a famous short sleeper. He described sleep as a “waste of time”.
On the other hand, Albert Einstein reported that he did his best thinking after 10 hours of sleep.
So what do we know about these long and short sleepers? Why do some people need 10 hours and some only 5?
The answer may be in their genes.
Sleep researchers studied one family consisting of 5 “normal sleepers” and two who only needed 6 hours per night. The two short sleepers (both ladies) routinely went to bed at 10 and were up and going at 4AM. Scientists found that the two early risers had a genetic mutation not shared by the other family members. The involved mutation was on one of a family of “clock” genes that regulate our bodies’ timing mechanisms.
Actually, to call this a “mutation” is somewhat misleading. It would be more accurately referred to as an infrequent genetic “variant” that results in a “short sleeper/early riser” temperament or personality.
So, to rephrase the original question, “What is the purpose of having some people needing to sleep less and others needing to sleep more?”.
As a rule of thumb, genetic variations, such as the one between short and long sleepers, must serve some Evolutionary purpose. While no one knows what that is, here is what I like to think.
Imagine yourself as one of those ancient cave people on whom Evolution conducted its cruel survival experiments.
You wake up one morning with your eyes frozen shut and you are literally freezing to death. But, just as your life is about to slip away, the cave begins to warm and a wonderful aroma drifts by. When your eyelids finally unfreeze, you see that those two nice early riser ladies have a fire going and are cooking up a delicious rack of cave bear bacon.
So you survive one more day thanks to those two early rising ladies who share what I like to call, “the breakfast maker mutation”.
In contrast to the short sleepers, scientists have yet to identify a genetic mutation specific to those of you who can’t get by without 10 or more hours of sleep. And it is difficult to imagine that the rest of your cave family would appreciate having you snoozing in while everyone else does all the hard work of survival.
But, in fact, long sleepers have some pretty good qualities. Einstein was a long sleeper. And he turned out to be pretty useful. In fact, High School and college students who sleep longer get better grades than their short-sleeping classmates.
Another good thing about the long-sleepers is that they tend to be relatively jolly and pleasant to be around. In contrast, some groups of short sleepers have been found to be more “neurotic”—crankier, grumpier, and definitely more irritating. You know the type. Out collecting the firewood and complaining that they are the ones doing all the work (which they probably are).
I’m sure that scientists will eventually discover the “long sleeper/late-riser” gene. Until then, I think I’ll just call it “The Happy Albert” mutation.
November 14th, 2012
Why does coffee keep you awake?
Your brain is powered by an enormous rechargeable battery. It is spent during the day and recharged while you sleep at night. After a good night of sleep we awaken feeling rested with our brain battery fully recharged.
Most of us, however, do not, in fact, wake up with such a well-charged battery. Rather ours is charged to the measly 50% we earned by staying up late doing nothing we are particularly proud of come morning. We are the coffee pot people. We are the ones who, after hitting snooze as long as we dare, finally begin the long bleary-eyed stagger towards the coffee pot. Because we know that, without this miraculous drug, we are doomed to stumble through the day like brainless zombies.
So, how does coffee work this magic?
Coffee can’t give us a fully charged battery. But it can trick our brain into thinking we have one. So when your brain takes a look at it’s battery meter, it sees 100% and so, turns off all the signals telling you to get back to bed right now.
But more than waking you up, coffee wakes you UP. After one cup of Joe your IQ shoots up 20 points and you suddenly you have the energy you used to have 10 years ago when Disneyworld was something you actually looked forward to.
You feel as if adrenaline is rushing wildly through your veins. Actually, that is because adrenaline IS rushing wildly through your veins. Coffee is not only a waker-upper. Coffee is an upper. An Adderall-like, pharmaceutical grade stimulant.
So, after that first cup(s) of java, you put the pedal to the metal and launch into your day. Whenever your energy begins to flag, you head back to the coffee (pit stop) and you are back in the race.
But somewhere down deep, you know this can’t go on forever. Eventually the truth comes out. As the coffee magic wears off, your mind realizes that it has been fooled (again). And, suddenly seeing that its battery is in fact, heading into the red, your brain simply slams on the brakes. The result of which is the inevitable end of the day, coffee crash.
Most of us accept that the game is up and head sluggishly back home where we lay down on the couch and once again watch mindless television shows until 1AM just like we did the night before.
There are always some of us, however, who, out of desperation or simple self-denial, refuse to go quietly into that good night.
I myself have been one of those people. I can vividly recall how absolutely confident I felt that, on the day before it was due, I could easily knock out that 20 page paper that I had been preparing to start for the past 8 weeks. (note: the positive impact of coffee on writing productivity was first recognized by the 19th century philosopher Balzac who wrote: “As soon as coffee is in your stomach, there is a general commotion. Ideas begin to move…similes arise, the paper is covered. Coffee is your ally and writing ceases to be a struggle”).
With that first cup of adrenaline coursing through my veins, I would write like a man possessed. Hour after hour, I would pound away; filling that computer with all the inspired ideas I had amassed over weeks of daydreaming about the brilliant paper that was now unfolding in front of my now wide awake eyes.
That is, until, about 8 pages in, the thoughts weren’t flowing quite so quickly. And each additional cup of coffee would result in less writing and more pacing.
And so it would go. The, oh so predictable, descent from 8AM “Superman” into 2AM ”Wired man”. And that brilliant paper I had imagined would begin to sound as if it was being written by someone for whom English was a second language.
So that is how coffee works. At least until it doesn’t.
WARNING. THIS NEXT SECTION IS ONLY FOR SCIENCE NERDS LIKE MYSELF. FOR ALL ELSE, NO AMOUNT OF COFFEE WILL SAVE YOU
Caffeine has three important effects: (1) wake you up, (2) help you focus, (3) get you moving.
The first effect is the result of caffeine’s ability to block adenosine receptors. You may recall that molecular processes throughout the body are primarily powered by ATP (adenosine tri-phosphate). ATP has been referred to as the body’s “molecular unit of currency”. Energy is transferred by the transformation of ATP into ADP (adenosine di-phosphate). The end product of this process is adenosine.
In one of the body’s many clever feedback loops, rising levels of adenosine informs the brain that ATP stores are running low and that it is time to sleep in order to build them back up. The more energy you burn during the day, the higher your levels of adenosine get, and the deeper your sleep. (side note, this is why we sleep better at night if we exercise during the day).
The second effect of improving attention and focus is the result of caffeine’s ability to stimulate the release of the neurotransmitters dopamine and norepinephrine. Not coincidentally, this is the same mechanism by which stimulants treat the symptoms of attention deficit disorder. (side note: my personal observation is that people who drink the most coffee are the most likely to have ADD).
Finally, caffeine “amps up the energy” by literally stimulating the adrenal glands to release adrenaline. How much does it release? A medium cup of Starbucks coffee will triple your adrenaline level.
October 24, 2012
What do dreams mean?
Let me start by answering the question “Why do we dream?”. Who better to answer this question than the famous scientist William Shakespeare?
“Sleep that knits up the ravelled sleave of care. The death of each day’s life, sore labour’s bath. Balm of hurt minds”(Macbeth, act 2, scene 1).
Of course Shakespeare isn’t really a scientist. A real scientist’s explanation would be even more incomprehensible. Shakespeare, being who he is, has to makes the same point three times, in three different ways. Essentially what he is saying is that sleep helps us to get over all the bad stuff we’ve been through. What Shakespeare doesn’t say, is that all this knitting, bathing, and balming happens when we dream.
My dreams often involve me being chased —a lot. And I am always running away from an endless assortment of angry people who want to kill me in every horrifying way my brain can come up with. But the funny thing is…. they never do. The bullets always miss. I always get away.
So the next night, I might have a dream in which I stand up to them (for some reason, this usually involves a sword). I don’t always win, but I never lose.
And over the years, I have won more often than not. And I have found more and better ways of evading the bad guys (last night it involved grabbing a rope hanging from a hot air balloon…or possibly a helicopter. I don’t remember.
So now in my real life, when bad things happen, I’m less inclined to run from them in my dreams. And when someone really……..upsets me, I am more likely to stand up to them (although, at this point, I rarely need a sword).
So, in short, dreams make all the bad things better. Heal our old wounds. Make it easier to handle the ……… stuff thrown at us each day.
So, getting back to the question of “what do dreams mean?” First off, all dreams have meaning—no matter how bizarre or difficult to understand. The meaning of some dreams can be pretty obvious. A 5 year old dreams about eating a piece of chocolate cake. No mystery there.
Most of my wife’s dreams, at least the ones she tells me about, are often quite straightforward as well. If she is having trouble at work, she dreams about what is happening at work. Others are more complex. In some of her dreams, I am either having an affair with another woman or I’m leaving her. I am usually in big trouble when she has one of these dreams.
How about the really complex, weird dreams? They all have meaning too, but the more complicated the dream, the more difficult it is to figure out what it is about.
The most confusing aspect of dreams is that they include elements of both the past and the present, mixed together to create experiences you’ve never had. For example, you could find yourself working at a job you had 9 years ago, and your boss is someone you knew when you were 10 (e.g. 1967).
That is, in part, because there is an area of your brain (the dorsolateral prefrontal cortex for you neuroanatomy junkies) that organizes your experiences by time—letting you tell the difference between what happened in the past and what is happening in the present. When you are dreaming, however, this particular area of the brain, simply turns off.
People and events in your dreams are connected not by the time they happened, but by the emotions you felt when they happened. It is likely, then, that the events of the dream are connected to other people or situations that have made you feel the same way.
So, in the example above, the guy that bullied you when you were ten, could be representing a previous boss who made you made you feel the same way, even if the boss at the job you had nine could have been a very nice, woman. But the appearance of this guy in your dream last night, probably means that the dream elements are connected by other experiences you’ve had that caused you to feel the same way. And furthermore, it is likely that you’ve recently been feeling bullied.
Although the current bully may not even be a specific person and may not even be connected to your work.
If you are confused by this and annoyed with me for confusing you, someone who is annoyingly confusing may be the star of your next dream.
You are welcome.
———-September 17, 2012
Why do some people sleep so soundly that it is difficult to rouse them, and why do others sleep so lightly?
The sound sleepers are the lucky ones. They usually marry one of the unlucky ones.
There are several reasons that some people are light sleepers. The first reason is that light sleeping can be written into your genes. Consider the sleep habits of newborns and young children. There have always been the “good sleepers” and the dreaded “bad sleepers”. This difference is easily apparent the first night they get home from the hospital. And then becomes increasingly apparent for the next 6,570 nights.
If it is genetic, there must be some adaptive purpose to having a group of light sleepers among the heavy ones. Imagine, for example, a tribe with nothing but sound sleepers; who are sound asleep while a bear is consuming their neighbor. Our survival is truly dependent on the light sleepers. Thank you light sleepers. And I’m sorry.
Under certain conditions, a sound sleeper can change into a light sleeper. I’m sure that foxholes were filled with light sleepers. Who wakes up when the baby cries? Mom. How many marriages have been strained when Mom believes that Dad is just pretending to be asleep when the baby cries? The truth: women are wired differently than men. Studies of brain activity when hearing a baby cry: Mom: entire brain suddenly lights up like a one hundred thousand watt flood lamps. Dad: 20 watt light bulb
Interestingly, once you have become a light sleeper for an extended period of time, you may never be able to go back. Many mothers can attest to this. Research has found that formerly sound sleeping women, become permanently light sleepers once the kids arrive.