Wednesday, April 23, 2014

Obstructive sleep apnea and growth hormone

Growth hormone (GH) is secreted at night during our deepest levels of sleep. As the name implies, GH is involved in growth of our bodies. Too much GH as a child can result in a condition called acromegaly. The actor Richard Kiel, who played the character Jaws in two of the James Bond movies, has this condition. Too little GH can also negatively impact cardiovascular health as well as effect carbohydrate, fat, and lipid metabolism. GH is part of a group of hormones that include Insulin-like growth factor-1 (IGF-1) and IGF-1 binding proteins.

Obstructive sleep apnea (OSA) could reduce GH secretion due to the brief arousals from sleep, especially deep sleep. OSA can also affect GH levels by the repetitive oxygen level drops. It's been theorized that regular CPAP use may reverse the effects of OSA on GH. Previous studies have been inadequate to answer this question definitively. This study sought to determine if long term CPAP affects GH levels.

Researchers performed a randomized, double-blind, sham-controlled parallel group study. The participants were all men with moderate to severe OSA. They were randomized to receive either 12 weeks of real or sham CPAP. At the end of the 12 week period, all participants were put on real CPAP for another 12 weeks. The results showed that GH secretion was higher in those treated with real CPAP for 12 weeks compared to sham CPAP. Interestingly, the increase in GH was not due to improvements in the amount of deep sleep. Instead, the improvements in GH were associated with reduction in the oxygen level drops. Another interesting result was that the participants used real CPAP only 3.6 +/- 1.9 hours per night and the sham CPAP only 2.8 +/- 2.1 hours per night. Since most people sleep 7-8 hours per night, that amount of CPAP usage is low, yet the therapy still seemed to have a positive effect on GH.

Wednesday, April 16, 2014

Sleep is the new frontier of medicine

This week I am just posting a link to an article that discusses how sleep is the new frontier in medicine. It's a nice review of the importance of sleep, and how sleep affects so many different aspects of our physical and mental health.

Wednesday, April 9, 2014

Sleep loss and metabolic syndrome

Metabolic syndrome is a chronic disorder characterized by abdominal obesity, impaired blood sugar metabolism, high cholesterol, and high blood pressure. Here is an article about sleep loss and it's affect on our metabolism. The article is a review of the observational studies that examine the relationship between sleep deprivation and metabolic syndrome. The authors discuss some of the studies that show that acute sleep loss is linked with obesity, type 2 diabetes, cholesterol problems, high blood pressure, and even death. Of note, some of the studies show increased rates of some of these issues when people report sleeping less than or more than a specified "normal" amount of sleep. So it's not just sleep loss that is linked to problems, including mortality.

The authors note that sleep loss can affect appetite, food intake, physical activity levels, and energy expenditure. Again, these are short term studies and the reasons for the changes are not entirely clear. Results sometimes are conflicting, such as some studies showing higher levels, and other studies showing lower levels of appetite regulating hormones.

The authors conclude that sleep loss may be a "promising target for the prevention, and probably the treatment, of the metabolic syndrome and its components." Perhaps that is the case, but telling people to get more sleep is unlikely to improve their metabolic syndrome. It's certainly more complicated than that. Diet and exercise are just as important, and most likely much more so than just getting more sleep. I concede that insufficient sleep may contribute a small part to metabolic syndrome, but more long term studies are needed. And I agree with the authors when they conclude that ongoing and future studies will show whether interventions to improve sleep duration and quality can prevent or even reverse adverse metabolic traits."

Wednesday, April 2, 2014

9/11 and sleep apnea

Here is an article about how workers who were first responders to 9/11 have elevated risk of sleep apnea and post-traumatic stress disorder (PTSD). The article does not go into detail about the mechanism of action. I wonder if the rate of sleep apnea is higher due to localized inflammation in the upper airway due to the particulate matter inhaled at the scene. I could also envision higher rates of pulmonary disease from inhalation of particulates, but that was not mentioned in the article.

Wednesday, March 26, 2014

Blood sugar control and obstructive sleep apnea

Human sleep can be divided into two different stages, non-REM sleep and REM sleep. During REM sleep is when most dreaming occurs. And while we dream, our brain temporarily paralyzes our muscles to minimize potential harm that would occur if we acted out the dreams we had. However, when the throat muscles get paralyzed in REM sleep, the throat becomes even more floppy, and obstructive sleep apnea (OSA) can be more severe. In some patients, the difference in OSA severity from NREM to REM is quite striking - some patients have OSA confined almost exclusively to those periods of REM sleep.

Some sleep researchers feel that OSA confined only to REM sleep may not be as serious as OSA that is present in both stages of sleep, as I have blogged about before. But in my experience, patients that treat their REM sleep-related OSA often have an improved quality of life.

This article showed that the more severe the OSA is in REM sleep, the worse control of diabetes. It's not clear why that would be, but the findings do not support the thinking that REM sleep OSA is less serious. The study authors point out that since most REM sleep occurs in the second half of the night, patients who don't use their CPAP all night may be at greater risk of having less control of their blood sugars.

Wednesday, March 19, 2014

Weight loss and obstructive sleep apnea

Most people I see already know that obstructive sleep apnea (OSA) is related, at least in part, to elevated weight. Many of my patients start coming to my clinic for help after their OSA symptoms have worsened. Almost all of them report weight gain that occurred as the OSA symptoms worsened. Part of my treatment options, at least for mild to moderate OSA is weight reduction. Easier said than done, however. And if my patient has severe OSA, weight loss alone may not be enough to eliminate their OSA.

This study confirms what I said above. It showed that even moderate weight loss, if maintained, can eliminate mild OSA. The key here is maintaining the weight loss. Many of my patients are able to temporarily drop weight, only to regain it again.

Wednesday, March 12, 2014

Obstructive sleep apnea and multiple sclerosis

Multiple sclerosis (MS) is a neurological disease thought to be an autoimmune disorder. It causes a variety of symptoms, with a common one being fatigue. Obstructive sleep apnea (OSA) also can cause fatigue. This study sought to examine the relationship between fatigue, MS, and OSA. It was performed at University of Michigan's Neurology Department. MS patients were surveyed about OSA and fatigue. Results showed that 1 out of 5 MS patients reported a diagnosis of OSA. This is higher in the general population. Also, the researchers found that an even higher proportion of MS patients were at risk for having OSA based on a commonly administered questionnaire (the STOP-Bang). Finally, OSA was a predictor of fatigue after adjusting for other clinical and sleep related predictors of fatigue.

What the results mean is that neurologists and other physicians who care for patients with MS should not use the MS as the only reason for a patient's persistent fatigue. OSA could be contributing and the patient may benefit from a sleep evaluation. OSA is treatable and some of the fatigue may improve with OSA therapy.