DIABETES & SLEEP
[by Tamara Sellman RPSGT CCSH for Advanced Cardiovascular Sleep Disorders Center]
People who don’t sleep well may be setting themselves up for problems with insulin resistance.
Sleeping well can be defined as getting adequate, consolidated sleep every night. Consolidated sleep simply means that one sleeps without interruption for the full night.
If you don’t enjoy consolidated sleep most nights, and know you aren’t getting at least 7 hours of sleep at night, please read on.
What is insulin resistance?
All human bodies generate insulin, which is used to stabilize blood sugar effectively. Blood sugar (glucose) is used by all organs and cells as fuel, but too much or not enough can put the body into a state of stress.
When insulin resistance occurs, the body may still produce insulin, but it fails to use it effectively to balance glucose levels. These levels build up in the blood as a result, and aren’t absorbed for use as fuel by the organs and cells. When this occurs repeatedly over time, prediabetes and type 2 diabetes can develop.
DOES POOR SLEEP INFLUENCE INSULIN LEVELS?
Research at Cedar-Sinai Medical Center published in 2015 found that even one night of sleep deprivation decreased insulin sensitivity by 33 percent in animal subjects. By comparison, 6 months on a high-fat diet decreased the subjects’ insulin sensitivity by 21 percent.
Chronic sleep loss, or sleep deprivation, is defined as sleeping less than a total of 7 hours of sleep a night. Given that a large percentage of Americans routinely sleep less than 7 hours a night, this news regarding insulin resistance and its relationship to poor sleep is very concerning.
Why does poor sleep lead to insulin resistance?
People who are sleep deprived experience increased levels of the hormone ghrelin, which is known for stimulating the appetite.
When ghrelin levels increase, we crave fatty or high-carbohydrate foods as a response to a cellular need for fuel. But higher ghrelin levels also lead to a surge in the bloodstream of the stress hormone, cortisol. High levels of cortisol make the body less tolerant to glucose and can negatively influence levels of blood glucose between meals (or while “fasting.”)
Meanwhile, mixed signals in the organs of the endocrine system (responsible for metabolism) that are caused by sleep loss make the system less sensitive to insulin already available in the body (or “insulin resistant”).
Inadequate levels of insulin are released to counteract high levels of blood sugar. When these levels become too high, the sleep-deprived body fails to produce enough insulin to achieve a proper gluocose-insulin balance.
Too much glucose in the bloodstream can be dangerous, even deadly. The body responds to this system-wide threat by entering a state of stress, working overtime to process and excrete the excess glucose.
This is the reason why people who are diabetic must use the bathroom many times a night; nocturia occurs as a result of the kidneys processing this excess sugar, which is eventually eliminated by frequent urination to regain a balance of glucose and insulin in the bloodstream.
Nocturia is a common cause of sleep fragmentation, in which sleep is interrupted all night long. Broken sleep leads to less sleep and fewer cycles of complete sleep, which are necessary for optimal health and well being.
THE CIRCADIAN SYSTEM AND METABOLISM
Sleep is intended to be a time for cellular rejuvenation and the conservation of energy. During normal healthy sleep, our metabolism processes shift due to circadian system regulation to achieve this.
Metabolism describes the way our bodies process energy (glucose). The brain uses more glucose than any other organ but uses significantly less glucose for at least half the time we sleep.
Only during REM (or “dream”) sleep does our metabolism peak. We also enjoy the release of human growth hormone (HGH) during stage 3 (deep) sleep. We need HGH for cellular regeneration and repair.
However, insulin resistance during this period of sleep occurs as well. Levels of blood glucose should also decrease as we sleep. However, these processes during sleep, which normally maintain a healthy metabolism, can be set off kilter in the presence of untreated sleep disorders.
3 sleep disorders related to insulin resistance
If you have trouble falling asleep, staying asleep, or waking up too early, then you are experiencing insomnia.
Generally, most people need to meet the demands of family life, work, or school, so they don’t have the option of sleeping longer into the morning to make up for lost sleep.
This means the tossing and turning results in nights where people are getting far less sleep than recommended (7 to 9 hours is the target).
One random night of sleeplessness is not problematic; it’s normal for most people. However, if you’re experiencing night after night of lost sleep, and it’s been going on for at least 3 months, what you’re experiencing is no longer a random case of insomnia, but chronic insomnia.
This practically guarantees you are sleep deprived and racking up a significant sleep debt. The longer you go without full nights of sleep, the harder it will be for you to “pay down” that sleep debt.
Sleep deprivation creates the proper conditions for all kinds of chronic health problems to develop, including insulin resistance.
CIRCADIAN RHYTHM SLEEP DISORDERS
These sleep disorders relate to how you match your sleep-wake process to your circadian rhythms.
The human body is born with an innate set of rhythms which coordinate (or entrain to) the light-dark cycles of the Earth (all living things are born with these rhythms). Humans are meant to sleep when it is dark and be awake and alert when it is light.
However, modern-day living throws this cardinal rule of healthy balance out the window. People travel cross-country and disrupt their circadian clocks as a result (jet lag). Or they work evening or overnight shifts and are forced to sleep when during daylight (shift work disorder).
Others experience circadian dysregulation through no fault of their own. Their rhythms are set “off schedule” as in the case of night owls (who have delayed sleep phase disorder) and early birds (who have advanced sleep phase disorder).
Or, their rhythms don’t shift at the same time ever (as in the case of those with non-24 sleep-wake disorder, also known as free-running disorder), or their shifts are random, with bedtime tonight being 3pm, tomorrow at 4am, and the next day at midnight (the culprit? Irregular sleep-wake pattern). [Learn more about these sleep disorders here.]
Whether sleep patterns are voluntarily “shifted” or are the domain of disrupted mechanisms in the brain, the people who suffer these sleep disorders generally don’t get enough consolidated sleep (to include all the sleep stages and cycles). They either sleep at the wrong time or interrupt their sleep-wake patterns to meet other demands.
As with insomnia, this unattended and perpetual loss of sleep turns into a case of sleep deprivation and accrued sleep debt.
On top of that, since sleep itself is guided by these built-in circadian functions, any disruptions to these functions mean sleep itself will fall out of balance (fewer cycles and stages that need to take place, but can’t).
It should come as no surprise that sleep breathing disorders can lead to all sorts of problems with metabolism.
Whether the apneas are obstructive in nature (meaning, they’re caused by blockages in the upper airway), or central (meaning, they’re caused by a dysfunction in the part of the brain that regulates breathing while you sleep), or mixed (a combination of both types of apneas), these repeating arousals from sleep guarantee two things: sleep deprivation and a steady stream of stress hormones in the bloodstream precisely when the body should be resting.
Those stress hormones are key to amping up problems with insulin-glucose balance. And for some, levels of blood glucose may spike during these late cycles in the sleeping period.
Add sleep fragmentation to the mix, and you can experience insomnia, which adds more stress to the environment.
When someone has untreated sleep apnea (regardless how severe), the organs that exist to manage stress, keep blood hormones stable, and regulate steady metabolism never get a chance to do their jobs due to all the stress caused by these repeated awakenings.
Take your sleep health seriously
Obesity Society spokesperson Caroline Apovian, MD, FACP, FACN, said in reference to the Cedars-Sinai study that “It is critical for health practitioners to emphasize the importance of sleep to their patients. Many patients understand the importance of a balanced diet, but they might not have a clear idea of how critical sleep is to maintaining equilibrium in the body.”
If you already experience any of these sleep problems (diagnosed or not), you’re certain to notice changes in your body, such as weight gain, lethargy during the day, cravings for high-fat and high-carbohydrate foods, and other symptoms that suggest your metabolism is off kilter.
Don’t hesitate to consult a physician about your concerns; early treatment for your sleep concerns can result in alleviating the problems of insulin resistance or preventing it from becoming a pre-diabetic, or even a diabetic, diagnosis down the line.
Which would you rather treat? A sleep problem which can be easily managed or even eliminated in some cases? Or a metabolic disease that is far harder to manage and reverse?
“Sleep disorders and the development of insulin resistance and obesity.” Mesarwi O, Polak J, Jun J, Polotsky VY. Endocrinology and metabolism clinics of North America. 2013;42(3):617-634. Retrieved from the web on Friday, April 6, 2018.
Broussard J. Cedars-Sinai Medical Center. Poster abstract presentation at: The Obesity Society Annual Meeting at ObesityWeek SM 2015; November 2-6, 2015; Los Angeles, CA.