The Science of a Good Night's Sleep
Understanding sleep and a few tips for a restful night
Posted Jul 02, 2011
Which wouldn't bother me too much, except that I put on a couple of pounds (darn cortisol) and vanity is a failing of mine. From medical training I'm an old hand at sleep deprivation. Now there are actually laws against the amount of work I did back in the day. On the ICU service, for example, we were there all day every day (with one day off a month, typically), and every third day we would be on-call, meaning we would get there in the morning, stay and work all night, and then work all the next day. I think I figured out the hours vs. my salary at the time and figured out I was making half the minimum wage. While there is some uproar in the medical community and a feeling that the new laws limiting medical work hours are destroying medical education, I don't disagree with those laws as a rule.
I happened to do my psych consultation service on some of the same floors where the medicine interns wore EEG leads post-call (meaning after being up all day and all night, and rounding on patients in the morning) as part of a study on resident work hours. Turns out they spent a good deal of those post-morning rounds walking around in phase I sleep. Since I'm sure most of you don't care for sleepwalking doctors in charge of communicating vital information about your admission and hospital course, I imagine you are probably in favor of laws controlling medical residents' work hours. You might be surprised by the response within the medical community. They want residents to suffer a bit - they think it makes better doctors. And working crazy hours does build confidence and experience faster than anything. However, I hope it is not terribly controversial to suggest that we not make new doctors at the expense of safety (too much).
Well, sleep! Which I am sorely missing. I'm not young anymore, after all. I have at hand a basic reference for the neurobiology of the circadian rhythms. It is from the supplements from the Journal of Clinical Psychiatry (which I normally throw away, as they are generally thinly-gilded advertisements for the pharmaceutical industry. And this supplement is no different- it came out in 2005, which was right about when Ambien CR and Rozerem (which is a sort of advanced form of melatonin I don't think I've every prescribed) were being marketed, and if you read the entire supplement you get statements about how cheap, long-used sleeping pills aren't FDA approved (of course they are not - they were generic long before the current FDA approval process, and who would bother to spend the several gazillion dollars needed for the current FDA approval process for generic medicines?) But, pharmaceutical advertising notwithstanding, the paper I'm referencing is rather too basic to be dangerous, and it is free (with free registration) for everyone, so let's call it egalitarian.
The neurobiology of sleep is nearly as simple as light and dark. We have, in our brains, right in the middle a bit above our eyes, a little area called the superchiasmatic nucleus. It is an area of about 10,000 neurons that runs our circadian rhythms. Without light stimulus, it tends to fire in a rhythmic pattern in a cycle of a bit more than 24 hours. Light stimulus will reign it in and keep it correlated with our natural light/dark cycles.
Light hits the retina of our eyeballs, which then sends a signal up through our optic nerve directly to the superchiasmatic nucleus. In the superchiasmatic nucleus of the brain, two proteins are bound together, which is called a dimer. This dimer is made in response to the light and is called CLOCK+BMAL1 (let me suggest that the scientist who named the CLOCK protein was a tad more poetic than the namer of BMAL1). BMAL1/CLOCK starts the day running by binding the so-called per/cry promoter regions in the nucleus, leading to the creation of the PER/CRY protein complex (there are in fact 2 pers and 3 crys, but let's just call it per/cry for simplicity's sake.) Got it? So you have light hitting your eyeballs leading eventually to the creation of a protein complex called PER/CRY.
If the PERs and CRYs don't bind together with other PERs and CRYs to form the dimer, they are broken down very readily. The dimer of PER/CRY is then translocated from the nucleus to the cytoplasm of the cell for daytime cellular activity. All right! Throughout the night, when no new PERs or CRYs are made, the dimers already in the cytoplasm slowly degrade, until light comes again and more new ones are made. Thus the cycle of life and light and dark. That, in a nutshell, is the circadian rhythm.
Under conditions of sleep deprivation, our circadian clock will keep us from getting too far out of whack from light/dark cycles. We will readily sleep in the wee hours of the morning (and in fact major industrial accidents such as the Exxon Valdez crash and the Three Mile Island radiation leak happened at 3-4 am - at least according to my book on chaos and sleep), and yet even if sleep deprived and given ample opportunity, we have a hard time sleeping during the "forbidden zones" of 9am and approximately 9pm.
And what of that famous pineal gland hormone, melatonin? It is secreted in response to dark, and light stimulus (such as checking the twitter feed on the ipad at 3am, or turning the hall light on to quell the 3 year-old's fear of the dark) will diminish melatonin secretion immediately. The human superchiasmatic nucleus (SCN) has a bunch of melatonin receptors (there are very few in the human brain outside this region). Melatonin signals the SCN to cool it and settle down for the night. Melatonin seems to sharpen the natural SCN response to light and dark. Without proper melatonin signaling, light and dark signals to sleep or wake up are attenuated, leading to night wakefulness and daytime sleepiness.
So what to do if you have insomnia? The first thing is to cut out any late night retina stimulators - like TV or internet. Music or low-light reading is probably okay. Our retinas were never designed for HDTV at midnight streaming so much signal straight into our brains (I'm reminded of when my oldest as a baby was awake at night, and my husband, trying to spare me, dutifully took her downstairs and began watching "Three Kings" with her at 2am - well, that Iraqi sun on the big screen TV at 2am did nothing for our baby's ability to sleep, and she was WIRED for several hours.) Do not turn on the lights for a midnight visit to the refrigerator or the restroom. I'm not entirely convinced that complete, black darkness is necessary given our ancestral propensity to sleep under the moon and stars, but as little light as possible is likely ideal.
Get rid of the clocks, too, if you can. I don't use an alarm and haven't for many years. If you need an alarm to wake up, you aren't getting nearly enough sleep in the first place. The last thing you need while struggling with insomnia is to keep looking at the clock glowing balefully at you in the middle of the night. It is also important to go to sleep at the same time every night and get up around the same time each morning if you have troubles sleeping. Getting rid of naps can also help, though biphasic sleep (meaning an afternoon siesta with a late bedtime or an early bedtime with a split night ) is another common and natural way to get in your 8 hours. In our past, people also went to bed earlier (no TV or electric lights or internet, after all), and it was considered normal to be awake for bit in the middle of the night, with the second half of sleep being less restful than the first.
If you struggle with insomnia, avoid alcohol and heavy sedatives if you can before bed. Alcohol will give you a deeper than normal first half of the night, then a more restless second half, resulting in poor sleep overall.
There is an online resource called "CBTforInsomnia.com" that has an inexpensive program to help with insomnia (I have no connections to this resource and receive no money from promoting it), and the advice there has helped several of my patients who have had a hard time sleeping.
Failing that, if you have a condition such as depression, anxiety, or bipolar disorder, sleep is exceedingly important. In these cases I sometimes feel it is prudent to prescribe sleep medicines (in fact, with an escalating mania, especially a psychotic mania, sleep medicines will nip it in the bud as quickly as anything else), but it is obviously not the ideal and is not a long term solution. It is also reasonable to use sleep medications for certain crisis situations (a death in the family, after losing a job, etc.) for a short while - sometimes short-term insomnia can become long-term insomnia, and if a few days of a sedative can prevent that, then it is well worth it.
My own preferred sleep remedy is magnesium supplementation. I take a few hundred milligrams at bedtime, and as long as I resist the temptations of the internet and the children don't wake me, I can be up and well-rested the next morning. Some people also like chamomile tea, or even smelling lavender oil. Routine is helpful. Seth Roberts has found that if he stands up all day or stands on one foot 3-4 times a day for several minutes, he sleeps much better. Hey, doesn't have any side effects so it seems like it would be worth a try.
Good luck, and sweet dreams! More sleep-related posts to come.
Copyright Emily Deans, M.D.