[ed note: Michael Jorrin, who I like to call “Doc Gumshoe”, is a longtime medical writer (not a doctor) who shares his thoughts with us from time to time, generally on non-financial topics in health and medicine (as today, though he mentions a couple publicly traded companies). His words and opinions are his own.]
Let’s start with a little case study. Our subject is a healthy male in his 20s. On Saturday night, he and his wife go to a triple feature (three excellent French movies from the 1930s, Marius, Fanny, and César, directed by Marcel Pagnol and starring the famous Raimu), which lets out at about 3:00 AM. They then go to a neighborhood all-night coffee-shop, appropriately called “Fanny’s Say No More,” for a little something, because they have developed a lively appetite. They fall into bed about 5:30 AM, and don’t rouse themselves until almost 3:00 in the afternoon the next day. They laze about on Sunday and hit the sack at a more or less normal hour, elevenish, because Monday morning looms.
However, our young man (okay, I’ll confess, it’s me) gets a truly lousy night’s sleep Sunday night – tosses and turns, lies awake and listens to the tiny hum of the electric clock and the creaking of the bed-springs, falls into a deep sleep just as the alarm goes off, and is a zombie all day Monday.
So Monday night, he and his spouse, who also slept badly Sunday night, determine to get a really good night’s sleep. They grab a quick bite and are tucked in by about 9:00 PM, expectantly waiting to be enfolded in the arms of Morpheus. But Morpheus doesn’t do his job. Sleep comes in snatches, far from satisfactory. Our young man’s spouse gets up and takes something from the medicine cabinet, comes back to bed and goes to sleep, but our subject abstains and suffers. Tuesday is another zombie day for him.
Tuesday night comes. Our subject is understandably anxious. Has he become, suddenly, an insomniac? Where has balmy sleep gone? His wife doesn’t seem overly concerned – she, after all, slept pretty well. They have dinner and get ready for bed. As they are about to get under the covers, our subject’s wife suggests that our young man might just consider taking half a Valium tablet, which is what she took the preceding night. He reluctantly agrees, cuts the tablet in half with his nail scissors, and swallows the mutilated pill. And almost before he takes the few steps back to bed, he feels the waves of blessed sleep washing over him.
So, what does this tell us, if anything, about dealing with sleep issues?
First, and most obvious, it tells us that at least some of the efficacy of sleep medications is due to the placebo effect. Valium (diazepam) is not, strictly speaking, a “sleeping pill.” It is a drug in the benzodiazepine class and is classified as an anxiolytic, meaning that the specific mechanism is to reduce anxiety, which of course can be a cause of insomnia. We’ll talk later on about the different types of drugs, medications, supplements, that can be used to help with sleep problems. But it clearly was not the physiologic effect of the drug that put me to sleep – it was the feeling of relief that swept over me that I had taken a drug that would put me to sleep.
For many people, I suspect, taking a sleeping pill is just part of their bedtime routine, like brushing their teeth. The physiologic effect of the medication combines with the comforting sense that they have made the necessary preparations for enjoying a good night’s sleep. And, indeed, that combination works fairly well.
Second, and also fairly obvious, is that when I went to bed on that Sunday, I wasn’t anywhere near feeling “sleepy.” I hadn’t done much of anything at all that day – no work, no exercise, just a lazy day with the Sunday paper. I’d only been awake for about 8 hours, and I didn’t need any sleep just then.
Third, and not so obvious, but something that points to one of the fundamental issues in sleep, is that we humans seem to be programmed to sleep in the night and be awake in the daytime. As far as we know, every organism on our planet demonstrates some kind of response to the earth’s 24-hour rotation and the alternation of light and darkness, although not every species manifests the same sleeping-waking response as we humans.
This response is known as the Circadian rhythm, and in our species it’s controlled by a cluster of brain cells called the suprachiasmatic nucleus, or SCN. This little bundle dwells close to the optic nerve, which tell the SCN whether it’s light or dark. In turn, the SCN sends little signals to other brain departments. When it’s dark, the SCN signals the pineal gland to secrete melatonin, which makes us sleepy. When it’s light, the SCN triggers the release of cortisol, which is involved in a number of wakeful and active responses.
Related to this is the activity of the two divisions of our autonomic nervous system. The autonomic nervous system, in case you had forgotten, is the one that keeps our body functioning without our consciously having to tell it to function. It regulates our breathing, our heartbeat, our digestion, our vision, our glands, our bladders, our metabolism – in fact, most of what keeps us going. The autonomic nervous system has two separate and independent components – the sympathetic nervous system, and the parasympathetic nervous system. The sympathetic nervous system runs through the spinal nerve and its branches, while the parasympathetic nervous system takes off from the cranial nerves and mostly operates through a separate system, employing the vagus nerve for about 75% of its functions.
This is important, or at least interesting, because the functions that the sympathetic nervous system manages are primarily associated with waking, and those the parasympathetic nervous system manages are associated with sleeping. Here’s a quick breakdown:
Effects of the autonomic nervous system on various organs
|Organ system</td>||Sympathetic nervous system||Parasympathetic nervous system|
|Heart muscle||Increased rate and force of contraction||Slowed rate and force of contraction|
|Lungs – bronchi||Dilated||Constricted|
|Lungs – vasculature||Mildly constricted||Mostly dilated|
|GI tract||Decreased peristalsis and tone||Increased peristalsis and tone|
|Liver||Glucose release||Slight glycogen synthesis|
|Kidney||Decreased output and renin secretion||None|
|Basal metabolism||Increased as much as 100%||None|
|Skeletal muscle||Increased strength||None|
So what does that tell us? The sympathetic nervous system prepares us to deal with the needs of our waking, daytime activities. The heart beat is faster and stronger, blood pressure increases, lung capacity increases, the liver releases more glucose for energy, and our skeletal muscles are stronger. In contrast, the parasympathetic nervous system takes over while we rest and sleep. The heart slows down, blood pressure drops, breathing slows, the liver stores glucose as glycogen, and we continue to digest whatever food we’ve taken in during the day.
Regardless of when we actually tumbled into bed, the sympathetic nervous system generally starts to get us ready for the new day quite early in the morning. It doesn’t wait for the alarm clock or the morning coffee. Many people are familiar with the sensation of a somewhat more rapid heartbeat well before they’re ready to hop out of bed, and in people who are at risk for cardiac issues, the dawn hours are prime time for acute coronary syndromes.
Without going into more abstruse medical detail, the particular agents responsible for these sympathetic nervous system effects are known as adrenergic agents – norepinephrine and epinephrine – and these act on adrenergic receptors, designated as alpha and beta receptors. The beta adrenergic receptors in particular are the ones that activate those waking-up effects – the faster heartbeat, the greater lung capacity.
The parasympathetic nervous system works mostly through acetylcholine, and its effects are termed cholinergic. Besides the effects of acetylcholine on the sleeping / waking cycle, acetylcholine is also involved in memory and learning. There’s a theory that we take in information when we’re in the waking phase and the adrenergic agents are in control, and we process it and file it away when we’re in the sleeping phase and acetylcholine is doing its job. Of course, it’s not as though there’s a moment when one phase switches off and the other switches on – we secrete both neurotransmitters most of the time. It’s just a question of which phase is dominant.
So, returning to our case study, it seems that our subject went to bed at 5:30 AM on that Sunday just about when his sympathetic nervous system was prompting him to rise and shine. He then spent more than 8 hours in bed, and he was definitely zonked. But it wasn’t the most restful sleep. In this sense, his experience was similar to that of lots of people who have sleep problems due to such things as jet lag and shift work.
Dealing with jet lag and shift work
The challenges presented by these two situations are different in a number of respects, one of which is fundamental. The individual taking an all-night flight from Logan to Heathrow, arriving at 6:15 AM GMT, and expecting to make a coherent presentation at that eminent institution on Threadneedle Street at half-past nine, does indeed face a staggering challenge. But she ought to have taken the plane a day before, had a nap in her hotel, done a bit of shopping at Jigsaw, and had a bite of dinner at Simply Nico’s. If she had then gotten up in the morning (and if it has been a tolerably nice day in London), exposure to daylight might have got her cortisol flowing just a bit in time to perform decently. It would also have helped a good deal if in the days prior to setting off on her trans-Atlantic jaunt, she had tried to go to bed and get up just a bit earlier, so as to reset her own Circadian rhythms to sync up with Greenwich Mean Time. Granted, this is not easy, and life definitely gets in the way.
Jet lag is not a long-term sleep problem, even for people who are constantly jetting around the planet on highly important missions. I know of people who make a point of staying on Eastern Standard Time no matter where they are. They fly to London and take their morning meeting at 3:00 PM EST, have lunch at 6:00 PM, dinner at midnight, and fly back to Eastern time without losing much sleep. There are ways to lick jet lag.
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Shift work is much more difficult. Persons on the midnight-to-8:00 AM shift not only have to stay awake at work, but then go home and try to get some sleep during the hours when they would prefer to be awake. They’re in conflict with their Circadian rhythms, and also possibly with family members, noisy neighbors, and the matitudinal chirping of the birdies. Also, shift work usually is on a rotating basis, so that the person who’s on the graveyard shift for a month or so then changes over to the 8:00 AM to 4:00PM shift for a month, and then to the 4:00 PM to midnight shift. (I’m treating these as though they were simple 8-hour shifts, but of course the shifts are longer, to permit meal breaks, and they also often overlap.) In any case, what happens to shift workers is that just about when they get slightly adjusted to their disjointed sleeping / waking cycle, it gets disrupted again. And again and again.
For shift workers, staying awake during the graveyard shift, and then while driving home, may be a bigger challenge than getting some sleep during their off hours. The usual remedy is coffee, and there’s no question that caffeine helps some people stay awake and alert. For people who don’t like coffee, there are lots of ways to get caffeine without drinking coffee. Straight caffeine is available over the counter in the form of tablets such as No-Doz, each tablet of which consists of 100 mg of caffeine – approximately the same as a cup of coffee. Energy drinks, e.g., Red Bull, contain just a bit less caffeine per serving – about 80 mg. Drip coffee contains more caffeine than perked coffee, and espresso even more. Dry tea contains more caffeine by weight than coffee beans, but brewed tea doesn’t use that much dry tea, and a cup of tea usually has only a bit more caffeine than a cup of decaf coffee.
How does caffeine keep us awake?
The chief mechanism of caffeine is to dial down the activity of a neurotransmitter called adenosine. Adenosine plays a number of different roles in the body, and the adenosine phosphates – mono-, di-, and tri-, or AMP, ADP and ATP – are central to our metabolism. In the brain, one of the things adenosine tends to do is put a sort of damper on some forms of neuronal activity – in other words, it quiets down the brain and permits us to go to sleep. Caffeine blocks adenosine receptors, inhibits that quieting effect, and helps keep us alert and awake.
The effects of caffeine vary considerably among members of our species. I, for one, rely on my morning coffee to get me going (although that might be a kind of placebo effect – it’s the blissful aroma of that blend of Kenya and Vienna Roast coffee that starts my day). But I can usually drink a double espresso after dinner and sleep the sleep of the just. My wife, however, is reluctant to drink any coffee at all much past noon lest she have a problem falling asleep.
Which takes us back to the shift-workers’ dilemma: if they rely on coffee or caffeine in any form to stay alert during their shifts, how long will it be before they feel dozy and relaxed?
Perhaps because of the unpredictability of caffeine, many people employ other strategies to stay awake, whether for shift work, studying, driving, or any other activities. We will avoid discussing the extreme cases, since after all our principal focus in this piece is sleep, and not staying awake. In passing, we should acknowledge the use of amphetamines and similar agents that are primarily intended for the treatment of attention deficit disorder, e.g., Adderall, Ritalin, Vyvanse and the like. Short-acting formulations of these drugs may be used to keep a person awake and alert without carrying over and seriously interfering with sleep time. The abuse of these drugs is widely recognized, and is related to what many consider the over-diagnosis of ADD and ADHD – which is another subject for another time.
However, the need for something that helps people stay awake brings me to a relatively new drug, with an entirely different mechanism of action, which, as it happens, may also be employed to help people get good sleep.
Modafinil and orexins
Modafinil (Provigil, Alertec) and armodafinil (Nuvigil), both from Cephalon, wholly owned by Teva Pharmaceuticals, are relatively new stay-awake drugs that have gotten a great deal of attention lately. Modafinil was FDA approved for narcolepsy in 1998 and for shift-work sleep disorder in 2003. Armodafinil is the R-enantiomer of modafinil, meaning that it consists of only the right-handed version of the molecule (thus R-modafinil or armodafinil) . In many instances, the effectiveness of a drug depends on the precise shape of the molecule, and the precise way it locks with its targets. Two molecules can have the identical chemical composition, but be exact mirror images of each other. One locks with the target while the other does not. Think of the way a key fits into a lock: it can be cut in the same way, but if the grooves are on the wrong side, it will simply not go into the lock. Modafinil is the so-called racemic compound, consisting of both the right- and left-handed molecules, while armodafinil consists of only the molecules that fit the target.
Modafinil (and armodafinil) have been referred to as Viagra for the brain – they are stimulants, and may work by activating neurons called orexins (sometimes also called hypocretins, but we’ll stick with orexins). Orexins extend their axons to various parts of the brain that are involved with wakefulness and attention, and activation of orexins increases the levels of dopamine and norepinephrine in those areas. And, as noted earlier, norepinephrine in particular is the neurotransmitter that stimulates waking physiologic functions such as heart rate, lung capacity, energy production, and muscle strength. So far, these agents have not demonstrated much risk for abuse, unlike the amphetamines and other stimulants, which are commonly abused.
The side effects of any stay-awake medication are difficult to separate from the inherent effects of not getting enough sleep. The most frequent adverse event in clinical trial patients taking modafinil was headache, experienced by 34%; however, 23% of patients taking placebos also experienced headaches. Most other adverse effects were in the single digits.
What is particularly interesting about modafinil is that it gives us insight into the connection between orexins and sleep. If activating orexins can help promote wakefulness, would it not be possible that blocking the activity of orexins would promote sleep?
Sleep promoting mechanisms
Most sleep medications have worked by means of the neurotransmitter gamma-aminobutyric acid, or GABA, which is the chief inhibitor of neurons. The drugs that had this effect were discovered long before the identification of the mechanism. It was found that barbiturates induced sleep; only later was the inhibitory mechanism of GABA identified and studied. Barbiturates, such as Phenobarbital, Seconal, or Veronal, really do induce sleep. They do this by greatly slowing all transmission of signals in the cortex. Their defects are well known, including a tendency to be addictive; the celebrities who were hooked on barbiturates are many and notorious, e.g., Marilyn Monroe. And there is a tendency to overdose. It’s not easy to get the dose just right; people wake up sooner than they want to, or else they wake up feeling drugged.
Several other classes of sleep-inducing drugs also addressed GABA receptors, even though they may have different mechanisms of action. The benzodiazepines, such as Ativan (lorazepam), Dalmane (flurazepam), Halcion (triazelam), Restoril (temazepam), and others. These agents have a somewhat different effect than the barbiturates; their goal, rather than knocking you out, is to ease you into sleep by quieting down your anxieties. As noted earlier, they are primarily anxiolytics. Some people get habituated to drugs of this class; they find that to achieve the desired effect, they have to keep upping the dose. This might be considered a form of addiction.
And some antihistamines induce sleepiness, such as Benadryl (diphenhydramine), Desyrel (trazodone) and others; a major drawback of these is that in some people the effect lingers past the desired sleep period – i.e., you’re dopey the next day.
The blockbuster entry – I am not using that term loosely – was Ambien (zolpidem) from Sanofi, which also targeted GABA receptors. Currently, Ambien and Ambien CR account for about 70% of the 60 million or so prescriptions for sleep medications in the US. However, Ambien’s drawbacks are widely recognized, including a range of erratic