Wednesday, April 30, 2014

Insomnia and stroke

Sleep duration and cardiovascular disease gets lots of press, even though the studies are inconclusive. Some speculate a "U" shaped curve where too little sleep and too much sleep is associated with higher risk of cardiovascular disease. It's unclear, but insomnia gets linked to sleep deprivation, and thus the news runs with stories that insomnia can increase risk of cardiovascular disease. I have blogged about it multiple times, here, here, and here. There are relatively few studies that have examined the relationship between insomnia and stroke.

This study is a retrospective cohort study based in Taiwan. They looked at patients with a diagnosis of insomnia, and used a comparison group without insomnia. They excluded those patients with a known diagnosis of obstructive sleep apnea and those with previous diagnosis of stroke. Then they tracked the populations for 4 years to analyze the number of strokes that occurred. There were 21,438 subjects with insomnia diagnoses and 64,314 subjects without insomnia. As expected, prevalence of diabetes, high blood pressure, high cholesterol, depression, anxiety, and atrial fibrillation were all higher in the insomnia population. During the 4 year follow up period, 583 of the insomnia patients developed stroke, whereas 962 of the patients without insomnia developed stroke. The incidence rate was significantly higher in the insomnia patient group than in the group without insomnia.

Again, there are some important limitations in this study, some of which are not addressed by the study authors. One big one is that we really don't know if the patients had primary or secondary insomnia. For all we know, the patients with insomnia and stroke may all have had undiagnosed obstructive sleep apnea. Also, the researchers relied on a diagnosis code for insomnia, but that does not mean these patients had a clinical interview by a sleep physician to determine that diagnosis. We don't know who is making the diagnosis of insomnia or how it is being made. There seems to be too many details left out to make any reasonable conclusions. I do agree with the authors that we need to screen and treat insomnia. It's also important to make an accurate diagnosis.

The reason I harp on this topic is that many of my patients with chronic insomnia inadvertently worsen their insomnia by worrying about the supposed health effects of insomnia. The news media and magazine articles make "insomnia" sound so dangerous. But if these individuals have primary insomnia, then they are not necessarily at increased risk just from the insomnia alone.

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.