Wednesday, December 17, 2014

Insomnia and mortality

Chronic insomnia is a frequent problem, and several studies have attempted to link insomnia with medical problems, even death. However, it's not clear from these studies that the relationship is as stated. One methodology problem with these studies is the fact that most of them define insomnia based solely on the research subjects' description of their sleep quality. In other words, secondary causes of insomnia are not ruled out with objective testing like sleep studies. This abstract is about research done on subjects with chronic insomnia. I don't have access to the actual article, so my analysis of the study is limited. I can't tell from the abstract if the research subjects had secondary causes of insomnia ruled out with sleep studies.

Researchers used data from a community-based cohort and categorized subjects into having either persistent, chronic insomnia, only intermittent insomnia, or no insomnia. The researchers defined persistent based on the subjects' description of their sleep quality over a six year period. They then determined when the subject died for up to a 20 year period. The researchers also examined levels of a marker of inflammation called serum C-reactive protein (CRP). There were 1409 research subjects - 249 with intermittent insomnia and 128 with persistent insomnia. The results showed that the subjects with persistent insomnia were 58% more likely to die than those without insomnia. Those with intermittent insomnia were not more likely to die than those without insomnia. Of note, most of the deaths were cardiovascular. CRP levels were higher in those with persistent insomnia than in those with either intermittent or no insomnia. The authors noted that CRP levels were associated with increased mortality by themselves. However, adjustment for CRP levels did not notably change the association between persistent insomnia and mortality. Also, the results were adjusted for confounders such as age, sex, body mass index, smoking, physical activity, alcohol, and sedatives.

Wednesday, December 10, 2014

Obstructive sleep apnea and exercise capacity

This study is a cross-sectional evaluation of the relationship between obstructive sleep apnea (OSA) and exercise capacity. According to the authors, how OSA affects exercise capacity is not clear, as prior studies have conflicting results. In this study, researchers did sleep studies on participants and put them into two groups. Those with no or mild OSA, and those with moderate or severe OSA. They then measured their exercise capacity and compared the results. The main finding was that OSA was associated with decreased exercise capacity. And more severe OSA was associated with worsening exercise capacity. The mechanism behind why OSA would affect exercise capacity is not clear. The authors speculate that it could be due to changes in energy pathways, changes in muscle fiber structure, and/or changes in blood vessels in muscles - thought to be a result of low oxygen levels associated with OSA.

Wednesday, December 3, 2014

Smoking and sleep

This article describes research about reducing cigarette smoking in your sleep. The study in the article involves using a psychological concept of learning called respondent conditioning - think of Pavlov and his dog, at outlined in this Wikipedia article. The study participants were all smokers who expressed desire to quit. Researchers paired the smell of cigarettes with a foul odor when participants were asleep. Supposedly, the participants unconsciously associated the foul smell with the smell of cigarettes and ended up smoking 30% less. There was no smoking reduction in participants that were exposed only to cigarette smoke when asleep or if the participants were exposed to both smells, but while awake.

Two other interesting points about this study. The first one is that the participants did not remember the smells they were exposed to in their sleep. Also, it appeared that a light stage of non-dream sleep was was the most effective stage of sleep that was associated with reduced smoking. The authors concluded that conditioning can occur in sleep and that this technique may be used in other addictions.

Wednesday, November 26, 2014

Adenotonsillectomy and asthma in children

Some research studies have demonstrated an association between obstructive sleep apnea (OSA) and asthma. It's not clear why they are linked - it could be that both involve inflammation. OSA is also associated with obesity, which is linked to asthma. The most common treatment for OSA in children is the surgical removal of adenoids and tonsils, referred to as an adenotonsillectomy (AT). This study looked at historical medical and pharmacy records of children with asthma who did and did not have AT. The data in this study was from quite a large database, and the children who had AT were matched with those without AT.

The results showed that asthma flare-ups were worse in children the year prior to AT. However, after AT, asthma flare-ups declined significantly, to levels similar to the kids with asthma who did not receive AT. A similar decrease was seen in asthma medication refills in those children who underwent AT.

The study authors conclude that the presence of OSA can worsen asthma control in children, and that treatment of the OSA with AT may reduce asthma flare-ups. The authors appropriately caution that prospective studies will be needed to establish a causal relationship.

Wednesday, November 19, 2014

Sleep apnea and sex

Studies have shown that obstructive sleep apnea (OSA) increases risk of erectile dysfunction (ED), and treating OSA with CPAP can improve ED. And some of my patients with untreated OSA are just too tired to engage in sex. Finally, some of my patients are hesitant to start CPAP therapy because they worry it will interfere with their sex life. This is usually in my younger patients and some of it is a misunderstanding about when CPAP is worn. Some think it's supposed to be worn whenever they are in their bed, as opposed to just sleeping.

This article discusses research presented at a recent meeting. Researchers asked participants about their sexual quality of life. The participants all has OSA and were prescribed CPAP therapy. The researchers divided the participants into two groups - those that used the CPAP regularly and those that did not. Results showed no difference in sexual quality of life between the two groups. The conclusion was that CPAP did not interfere with the participants sexual satisfaction.

Wednesday, November 12, 2014

Postoperative outcomes in obstructive sleep apnea

Patients with undiagnosed obstructive sleep apnea (OSA) are thought to be at higher risk after an operation than those who have already been diagnosed and are being treated with CPAP therapy. Current practice guidelines recommend screening for obstructive sleep apnea before an operation, and starting CPAP therapy prior to surgery if feasible. Routine monitoring of patients with OSA is recommended after many types of surgery.

This study looked at historical outcomes after surgery that occurred before the implementation of the current practice guidelines. The study included data on adults and compared them to controls at low risk of having sleep apnea. The control patients were matched for the type of surgery, indication for the surgery, and date of the surgery.

The results showed that the risk of cardiovascular complications, primarily cardiac arrest and shock, was increased in undiagnosed obstructive sleep apnea but not diagnosed obstructive sleep apnea. However the risk of respiratory complications, primarily Acute Respiratory Distress Syndrome (ARDS) and acute respiratory failure was increased in both groups without significant difference in risk between them. Also, the results showed that increasing severity of obstructive sleep apnea, age, comorbid disease, and the type of surgery were also important risk predictors for postoperative complications.

The study was not designed to determine whether reduction in cardiovascular complications in those patients diagnosed with OSA was due to CPAP use as usage of CPAP was not measured immediately after surgery.

Wednesday, November 5, 2014

Energy drinks and athletes

Energy drinks like Red Bull and Monster are all the rage right now. Apparently, athletes are using them to enhance performance. This study assessed responses to energy drinks compared to placebo in athletes. The results showed athletes increased their "sporting performance by between 3% and 7%." Athletes were also able to up their performance at high intensities. The results also showed that "Energy drinks increase jump height for basketball players, muscle force and power for climbers and trained individuals, swimming speed for sprinter swimmers, hit force and accuracy for volleyball players, and the number of points scored in tennis.”

However, the energy drinks increased the frequency of insomnia, nervousness, and the level of stimulation in the hours following the competition. The researchers attributed all of the positive and negative effects to the caffeine in these energy drinks. The other ingredients did not seem to produce any benefit above the caffeine.