Wednesday, June 29, 2011

Stillbirths and Sleep

There was a study published in the British Medical Journal about sleep and stillbirth. One hundred and fifty five womean that were at least 28 weeks pregnant were asked questions about sleep position, sleep duration, time of day they sleep, snoring, daytime sleepiness, and urinating at night.

The results show that the risk of still birth is higher when pregnant women sleep on their back or right side, compared to their left side. The researchers think that on the back or right side, blood flow to the fetus might be reduced. Risk of stillbirth was higher in those pregnant women who slept regularly during the day and who slept longer than average at night. Also, there was higher risk of stillbirth in pregnant women who woke up to empty their bladders less than two times per night. Finally, there was no link between snoring, daytime sleepiness, and risk of stillbirth.

This was a small study and relied on women's self-report. Most people are not aware of how much time they sleep in any position, so these results should be interpreted carefully.

Monday, June 27, 2011

Sleeping Positions

Someone forwarded an article to me about the "best" and "worst" sleep positions. The article said that sleeping on your back is best and on your stomach is worst. They stated the "pros" and "cons" of all three positions, most of which I agree with. Of note, most of us change positions a few times each night, whether you remember it or not.

Sleeping on your back can reduce neck and back pain for some. If your head is elevated, back sleeping can decrease acid reflux disease. In theory, back sleeping could reduce wrinkles because gravity pulls your face skin onto your skull. The article also said back sleeping can be more supportive to your breasts, which could reduce breast sagging.

Side sleeping can also help some with neck and back pain, as well as reduce snoring. However, it can increase wrinkles and breast sagging because of the effect of gravity. Also, side sleeping is good for pregnancy, especially in the 2nd and 3rd trimesters.

Finally, stomach sleeping can further reduce snoring, but can exacerbate neck and back pain as the spine is not supported in this position.

Friday, June 24, 2011

Insomnia and Brain Cooling

A research study was presented at the annual Sleep meeting in Minneapolis about treating insomnia by cooling the brain - called frontal cerebral thermal transfer. The study included 24 patients, half with insomnia and half without. The study subjects wore soft, plastic caps with circulating water that could be cooled to different temperatures. The results showed that in those with insomnia that were treated with the maximal cooling temperature fell asleep in 13 minutes and slept 89% of the time they were in bed. This is compared to the subjects without insomnia who fell asleep in 16 minutes and slept for 89% of the time they were in bed.

The researchers do not know why the cooling helps but they do have a theory. People with insomnia have increased metabolism in the front part of their brain. And cooling that part of the brain may reduce metabolism enough to improve sleep quality. This cooling cap could be an alternative to sleeping pills.

Thursday, June 23, 2011

Restless Legs Syndrome and Erectile Dysfunction

A poster was presented at the annual Sleep meeting in Minneapolis involving research about restless legs syndrome (RLS) and erectile dysfunction (ED). Researchers studied 11,000 men with an average age of 64 years old and without ED, diabetes, or arthritis. The results showed that men with RLS were about 50% more likely to develop ED, even after controlling for age, weight, smoking status, antidepressant use, and other chronic diseases. Also, the more frequently the men experienced RLS symptoms, the more likely they were to develop ED. Researchers do not know why RLS and ED are linked, but some theorize that low dopamine levels could be involved. It is believed that low dopamine can contribute to RLS. It would be interesting to study whether medications that improve RLS that affect the brain's dopamine system can also improve ED.

Tuesday, June 21, 2011

Snoring and Carotid Artery Disease

There is an intersting article in the June edition of the Sleep Journal about how snoring damages the lining of carotid arteries, which are the large arteries in our necks that supply blood to the brain.

The authors of this study had already shown that heavy snoring is an independent risk factor for carotid atherosclerosis (hardening of the artery). It was postulated that the vibration from snoring damaged the lining of the walls of the carotid arteries, which than could lead to atherosclerosis.

In this study, researchers put a vibratory sound, similar to human snoring, next to the carotids in anesthetized rabbits for six hours. Just this one time exposure to snoring vibrations damaged the lining of the carotid artery. The results of this study are interesting because prior epidemiologic studies with self-reported snoring have been contradictory with regards to harmful effects of snoring. But it has been arugued that the reliance on self-reported snoring is inaccurate, particularly in the absence of a bed partner to hear the snoring. And objective measurements of snoring have not been a routine part of sleep medicine. The results of this study have public health implications, as snoring is estimated to occur in almost half of the population. If snoring does damage adjacent blood vessels, this could increase stroke risk. Therefore, as a field, perhaps it is time we sleep physicians developed ways to quantify snoring and to take snoring more seriously.

Sunday, June 19, 2011

Exercise, Diabetes, Sleep Apnea, and Death

I saw a report about a study presented at the annual meeting of the Endocrine Society. The study involved male veterans with diabetes and obstructive sleep apnea (OSA). Apparently, good exercise capacity is associated with a lower mortality risk in patients with type 2 diabetes. Also, studies have shown that patients with OSA have an increased mortality risk compared with those without OSA.

In this study, researchers measured the fitness levels of 567 male veterans averaging 62 years old. After taking other risk factors into account, like race, smoking, and medication use, the study results showed that men with low fitness levels had a 75% higher risk of death than those with high fitness levels. The change in death risk was proportional to the fitness level too.

This study is important because diabetes and OSA are both increasing in prevalence, probably a result of the increasing obesity rates. And as weight goes up, fitness levels generally go down. One thing I don't know is if the patients with OSA were being treated with CPAP, which might help lower their death risk, regardless of fitness level.

Friday, June 17, 2011

Sleep and Problem Solving

I haven't posted in over a week because I was at the annual Sleep meeting in Minneapolis. At the meeting, there were some discussion about sleep, memory, and cognitive performance. So I thought I would post about a recent study done in the Journal of Sleep Research.

In this study, researchers assigned a gambling game to college students. Some of the students learned how to play the game in the morning, and others learned how to play it in the evening. The students then played the game 12 hours later. There was a trick to beating the game, but the students were not allowed to figure that out until they played the game. The results showed that in those that learned about the game in the evening, slept on it, and then played in the AM, 80% of them figured out the trick to the game. In those that learned about the game in the AM and played in the evening, without sleeping on it, only 40% figured out the trick to the game.

The researchers concluded that sleeping on it improved the students' performance. Perhaps it's because during sleep, the brain is able to organize the day's memories, which could have a positive effect on functioning the next day. Research has already shown that memory and performance can be negatively affected by sleep deprivation. This study further enhances are understanding of how sleep can affect the way our minds work. Therefore, when you have an important decision to make or problem to solve, consider sleeping on it first.

Thursday, June 9, 2011

Circadian Rhythm, Gender, and Insomnia

There was a study done last month published in the Proceedings of the National Academy of Sciences about the differences in circadian rhythm between men and women. Our circadian rhythm is the 24 hour cycle that controls many of our bodily functions, including when we sleep.

For this study, the researchers observed the natural circadian cycles of men and women in a controlled sleep lab over 2 to 6 weeks. The results showed individuals circadian rhythms ranged from about 23.5 to 24.5 hours, and was unaffected by age. The circadian clock of women averaged about 6 minutes less than the men, and the women were 2.5 times more likely than the men to have cycles shorter than 24 hours.

The researchers do not know why women's circadian rhythm would be shorter than men's, but it could be related to female estrogen levels.

A circadian rhythm that is short could explain in part why some women may have difficulty maintaining sleep and early morning awakening. It also could mean that women might get sleepy earlier than men. Unfortunately, there isn't anything that can be done to change the length of your circadian rhythm. Practicing good sleep hygiene and listening to your body will help you sleep better.

Monday, June 6, 2011

Obstructive Sleep Apnea and Cancer

At the American Thoracic Society 2011 meeting in Denver, researchers presented interesting results about cancer in mice with experimentally induced obstructive sleep apnea (OSA).

In OSA, patients can have repetitive, brief episodes of low oxygen levels called hypoxia. Persistent, prolonged hypoxemia, as opposed to the repetitve type seen in OSA, has been shown to promote growth of cancer cells. But no study had demonstrated that the intermittent hypoxia in OSA could do this.

Researchers injected melanoma cells in mice. They exposed one half to normal oxygen levels for six hours, and the other half to 20 seconds of hypoxia, 60 times per hour for six hours to mimick what might occur in OSA. The results showed that the melanoma cells proliferated faster in those mice with hypoxia when compared to the mice that were exposed to normal oxygen levels.

This study involves two extremes - normal vs very abnormal, since experiencing 60 episodes of hypoxia per hour for 6 hours would be very severe OSA. We do not know if more mild amounts of hypoxia will also promote tumor growth - more studies will be needed to sort that out.

Saturday, June 4, 2011

Obstructive Sleep Apnea and Erectile Dysfunction

At the American Urological Association's annual meeting in Washington, DC this year, a study was done of 870 men with an average age of 47.3 years. Health screening revealed 63% of men had obstructive sleep apnea (OSA). I do not have more details about how the men knew they had OSA - 63% seems high.

After adjusting for their age and other health conditions (like diabetes, obesity, and smoking status), researchers found that those men with erectile dysfunction (ED) were more than twice as likely to have OSA than those without ED. The more severe the ED, the greater the likelihood of having OSA.

I use this fact in discussing OSA in my younger male patients, as any mention of ED can get them interested in diagnosis and treatment of OSA. The study does not state that OSA causes ED or is just associated with it. We also do not know if treatment will reverse ED.

Some of my female patients with untreated OSA complain about a diminished sexual libido. There could be a common, underlying mechanism in how untreated OSA impacts sexual functioning in both men and women.

Bottom line is that in men with ED, urologists and primary care physicians should consider untreated OSA as a possible contributor.

Wednesday, June 1, 2011

Researchers at the University of Louisville have found that a urine test can tell if children who snore have obstructive sleep apnea (OSA) or not. Apparently, there are different concentrations of stress-related proteins the urine of snoring children with OSA, than in snoring children without OSA. The researchers believe that the test is so simple, it could be performed in the home, like a home pregnancy test. It also might eliminate the need for a costly overnight sleep study to determine if children who snore also have OSA.

This study was published in the December 2009 edition of the American Journal of Respiratory and Critical Care Medicine, but I just saw a blurb about it from the University a few months ago. I thought that perhaps more information had come out about this, but a google search only showed the original findings from 2009. I guess we'll have to wait until more studies have been completed.