Insomnia Part II: Caffeine
The following is a collection of the research, thoughts and writings of some of the best sleep scientists and authors in the world today. My only contribution here, is to have put their words and works into a compact and accessible form. A list of those writers and scientists appears at the end of this blog for your further reading.
Quick Summary:
Caffeine gives energy, alertness, stamina, focus and concentration.
But does that come with a price? Yes, it does – a big price for us as individuals and for us as a society.
Psychoactive Molecules – Sleep and Wakefulness
Caffeine is an interesting little molecule. It binds to an important central nervous system receptor that normally binds the molecule adenosine. Adenosine starts building up and binding to its receptors from the time we wake up. As the buildup of adenosine increases throughout the day, we get more and more tired, most noticeably in the evening. This is called “sleep pressure.”
Caffeine is an adenosine antagonist. It binds to the adenosine receptors and blocks the attachment of adenosine. Caffeine gets in the way of adenosine. Adenosine builds up anyway and comes on like a flood when the caffeine is metabolized. This is the “caffeine crash.”
Both molecules are psychoactive. Adenosine is a central nervous system depressant, a sedative hypnotic which induces sleep. Caffeine is a stimulant which works by blocking the depressive effect of adenosine.
Adenosine slows our brain function and prepares us to go to sleep, if caffeine or other stimulant doesn’t get in the way. Caffeine blocks the signals to turn out the mental lights.
With caffeine on board, you may feel wide awake and alert, but all while adenosine is building up in the background. You’ve been temporarily tricked by caffeine. This trick gets reinforced by the fact that caffeine also increases serotonin, adrenaline and dopamine. The release of dopamine is typical of drugs of abuse and probably accounts for caffeine’s mood enhancing qualities.
Caffeine is habit forming, a mild diuretic, temporarily raises blood pressure and relaxes the body’s smooth muscle which may account of its laxative effect.
Most interesting is the targeted way that caffeine interferes with one of the most important biologic functions – Sleep.
Unsupervised Drug Study
The neurobiologist, Matthew Walker, in his book “Why We Sleep,” argues that the consumption of caffeine, the most widely used psychoactive stimulant in the world, represents the largest and longest unsupervised drug study conducted on the human race.
In the U.S., caffeine is the only psychoactive drug routinely given to children, mostly in the form of soda pop.
We now know the results of that study and if Walker is correct (my daily clinical observations say he is!), those results are downright alarming.
Caffeine, Interrupted Sleep and Disease
Does caffeine cause heart disease, mental illness, hypertension, etc. etc? No, not directly, but yes it probably contributes to these, and others, indirectly by the sleep fragmentation that it causes.
In pharmacology, it is well understood that the dosage of a drug can determine its action – a small dose may heal and a large dose may kill.
With that in mind, if coffee isn’t consumed to an excess, some research shows that it is actually associated with a reduction in breast, prostate, endometrial and colorectal cancer as well as cardiovascular disease, Type II diabetes, Parkinson disease and possibly depression and suicide.
BUT, as soon as caffeine interferes with sleep, even in the slightest – all bets are off.
We at the TMJ & Sleep Therapy Centre of Kansas are in agreement with Dr. Matthew Walker: We are here to alert the world to an invisible health crisis, which is that we are not getting nearly enough sleep and the sleep we are getting stinks and the principle culprit is caffeine. Caffeine itself may not be bad for you, but the sleep it steals from you may be deadly.
The research suggests that insufficient quantity and quality of sleep may be a key factor in the development of Alzheimer’s, arteriosclerosis, stroke, heart failure, anxiety, depression, suicide and obesity. The shorter you sleep, the shorter your life span.
None of the younger sleep researchers, I have professionally had contact with, consume caffeine.
Is My Sleep More Interrupted than I Think?
Questions to ask yourself, spouse, friends, children or grandchildren or anyone:
- Can I fall asleep easily?
- Do I stay asleep?
- Do I wake rested and ready for the day (without caffeine!)
Regarding “2.” above, the more interruptions of your sleep, of any kind, the poorer our quality of sleep.
Deep Sleep
These interruptions are called arousals. They disrupt the deep, slow wave which is so important to repairing and rejuvenating our bodies for the next day. During deep sleep, low frequency brain waves set out from the frontal cortex and travel to the back of the brain, synchronizing many thousands of nerve cells. This harmonizing of our brain cells in a sort of neural symphony, helps us to distill and consolidate the blizzard of information we have taken in during the day.
Memories are carried on these slow waves from sites of short-term, daily storage to more permanent locations. These are stored in their proper place or trashed; just like organizing your desktop at the end of your workday.
Microarousals, full arousals or deep sleep interruptions of any kind, corrupt this memory and learning storage process.
Fragmented Sleep and Aging
For most people, the quarter life of caffeine is about twelve hours. So, 25% of the caffeine in the cup of coffee you had at noon is still swimming around your brain at midnight. That could well be enough to wreck your deep sleep.
Coffee after dinner? Some people say they can drink coffee and go straight to sleep. Perhaps, but that will reduce you slow wave sleep by at least 15-20%. Dropping your deep sleep by that much is the equivalent of aging you by 15-20%.
More Reasons for Fragmented Sleep
Caffeine is not the only cause of our sleep crisis. Screens, alcohol (which is as hard on REM sleep as caffeine is on deep sleep), pharmaceuticals, noise, work schedules, poor nasal breathing, light pollution causing glare, skyglow, and over illumination and anxiety play a role in undermining the duration and quality of our sleep.
Caffeine the Two-Edged Sword
But caffeine is at of near the top of the list of culprits. Matthew Walker points out that if you plot the rise of Starbucks over the last thirty-five years and the rise of sleep deprivation, those lines look very similar.
Here is what is uniquely insidious about caffeine. It is not only a leading cause of sleep deprivation; it is the principle tool we use to remedy the situation. Most of the caffeine consumed today is being used to compensate for the lousy sleep for which caffeine bears responsibility. This means that caffeine helps to hide the very problem it creates. It also means that caffeine may be an offender in your insomnia.
Charles Sisler (who no longer uses caffeine) is a circadian rhythm researcher at Harvard Medical School. In a National Geographic article by T.R. Reed, he states, “the principle reason people around the world use caffeine is to promote wakefulness. At the same time, the principle reason people need that crutch is the inadequate and/or ineffective sleep that caffeine causes.” Isn’t this “Catch-22” the very dilemma faced by anyone using an addictive drug?
The Caffeine – Insomnia Spiral
Caffeine is only hiding or postponing our exhaustion by blocking the action of adenosine until liver removes the caffeine from circulation. When this dam holding back the pent-up adenosine floods the brain, you will crash – feeling even more tired than before that first cup of coffee, soda or tea.
There is no free lunch. The apparent energy achieved by drinking caffeine must be paid back, either by requiring more sleep or in accelerated aging. If this caffeine induced debt is not paid back, it may also be the cause of insomnia.
Acknowledgements: Michael Pollan, Christian Guilleminault, William Dement, Matthew Walker, Steven Olmos, Sigrid Veasey, Maiken Nedergaard, Allan Rechtschaffen, Charles Sisler, David Rapoport, David Gozal, Richard Lang, Tim Olds, Jodi Mindell, Michael Grandner and many others I failed to record in my notes as I prepared this blog.
Thanks to all of these researchers, clinicians, educators and writers for their dedicated efforts to improve the health and well-being of everyone on this planet. Thanks as well to the institutions with whom they are associated.
To Your Better Health,
Dr. Joe Baba for the Doctors and Staff or the TMJ & Sleep Therapy Centre of Kansas
