Friday, November 4, 2016

Common swift stays airborne for 10 months straight!

I know this article about birds isn't relative to human sleep (at least directly). I thought it was fascinating because as a sleep doctor, my first question was when do these birds sleep, if they can stay in the air for 10 months. All animals have to sleep, so they much be getting some sleep. Turns out they climb really high and then coast down for 30 minutes at least twice a day, presumably to take power naps. Scientists don't know for sure if the birds are actually sleeping, but this is their best guess, and it makes sense to me. Maybe the ornithologists need to do a portable sleep study on these birds!

Thursday, October 27, 2016

American Academy of Pediatrics Updates

Recently, the American Academy of Pediatrics released updated guidelines on two important issues related sleep. The first update concerned sudden infant death syndrome (SIDS). Here is a link to the guidelines.

The second update concerned media use in children and adolescents. The recommendations discuss sleep and other aspects of how media affects children. For younger children, here is the link. For older children and adolescents, here is the link.

Wednesday, September 7, 2016

High blood pressure medications and obstructive sleep apnea severity

Obstructive sleep apnea (OSA) is associated with high blood pressure (HTN). Studies have shown that OSA is independently associated with resistant HTN and it is believed that untreated OSA may worsen HTN. However, studies involving treatment of OSA with continuous positive airway pressure (CPAP) have demonstrated only modest improvement in daytime blood pressure in randomized control trials. some research first speculate that the relationship between OSA and HTN may be bidirectional.

With OSA, the muscles that make up the throat lose their home causing collapse of that area and reduction in airflow to the lungs. Research her as hypothesized that intensive blood pressure control may influence always say I stabilizing the upper airway. There is also evidence for the role of volume status affecting the severity of OSA. What this means is that some people have worse OSA when they have too much blood volume from conditions like heart failure or kidney failure.

This study theorized that it is at least plausible that intensive treatment of HTN may bring about improvement in the severity of OSA, either by volume control, stabilization of upper airway muscles, or perhaps because of some direct effect of blood pressure medications. The researchers conducted a systematic review and meta-analysis on this topic.

Although there were limited number of studies and the studies were not of high quality, though results revealed that there was a decrease in OSA severity after treatment with blood pressure medications. Of note, the decrease reached statistical significance but the researchers doubted if it would be clinically significant.

I wanted to blog about this study in part because because throughout my career as a sleep physician I have thought of the OSA-HTN relationship as more one way, with OSA contributing to HTN, rather than the opposite as suggested by the authors of this study. Certainly more studies will be required before any definitive conclusions can be made.

Friday, August 26, 2016

Snoring and obstructive sleep apnea

Snoring is a common problem among men and women and is one of the cardinal symptoms of obstructive sleep apnea (OSA). With the explosion of smartphones and the emphasis on in-home monitoring, sleep researchers have attempted to use measurement of snoring to determine risk of obstructive sleep apnea. It has been difficult to do this because not all people who snore have obstructive sleep apnea. In addition, sleep researchers don't agree on an objective definition of snoring or an established threshold level of loudness. The quality of snoring is determined by multiple factors including the stage of sleep, body position, use of alcohol or other sedating medications, and upper respiratory tract illnesses such as a cold. There is significant variation of snoring from night to night for no apparent reason as well. Finally, snoring can be chronic throughout the night or periodic meaning that there are periods of silence between snoring episodes. The periodic snoring may be more suggestive of obstructive sleep apnea.

This study evaluated the diagnostic value of periodic snoring sounds measured during home sleep apnea testing. Subjects that were at risk for obstructive sleep apnea were sent home with a home sleep study monitoring kit and worn while they slept. The home sleep study kit has a built-in microphone that is located on the chest to detect the snoring sounds. the results showed a strong positive correlation between the percentage of periodic snoring and obstructive sleep apnea severity (AHI). The correlation was strongest for younger subjects, females, and obese subjects. The researchers discussed that some women do not get evaluated for obstructive sleep apnea because they do not know that they snore or are embarrassed to report snoring. In my clinic, I find this to be the case as well. Therefore measuring snoring at home while the patient is asleep many help sleep physicians to recommend formal diagnostic sleep studies to accurately assess female patients without a strong history of snoring.

Friday, July 1, 2016

Sleep restriction and athletic performance

I used to run long distance back in my salad (younger) days. I read books and magazines about running and running performance. I remember reading something back in the 1980's about how sleep deprivation did not affect running performance.

However, here is an article about recent research showing small reductions in performance of elite cyclists with voluntary sleep restriction to 4 hours per night for 3 days. The researchers measured energy expenditure, maximal aerobic power, and time to exhaustion. However, I don't see any data about actual cycling performance such as time to complete a course, etc. Therefore, I am not sure if sleep restriction really impacts elite cyclists. I know that not getting enough sleep lowered my motivation to run the next day!

Wednesday, May 4, 2016

High blood pressure and insomnia

Insomnia refers to an inability to sleep the desired amount despite adequate allotted time in bed. People with insomnia often misperceive their sleep duration. Research studies have linked chronic insomnia with increased risk of high blood pressure (HTN). Sleeping less than 6 hours is considered being a "short sleeper" and is also associated with HTN.

This study looked at the association between short sleepers with insomnia and HTN. Participants underwent two consecutive in-lab sleep studies to objectively monitor sleep duration. They also had the participants record their subjective sleep duration with a sleep diary. Results showed that insomnia with objectively-measured sleep duration less than 6 hours was associated with increased risk (Odds Ratio 3.59) for HTN. This finding was independent of the following confounders: age, gender, race, body-mass index, frequency of sleep aid use, sleep apnea severity, daytime sleepiness, diabetes, high cholesterol, depression, alcohol use, tobacco use, or caffeine consumption.

The authors concluded that the results provide further support for measuring sleep duration objectively, rather than subjectively for those patients with chronic insomnia. This means the authors are advocating for sleep studies in the evaluation of chronic insomnia to help determine morbidity risks associated with the insomnia.

Wednesday, April 20, 2016

Sleep duration and sleep hygiene differences in homeschooled vs public / private school students

Adolescents tend to be a sleep-deprived bunch. I know I was when I was in high school. Adolescents tend to stay up late, in part because of a biological shift in circadian rhythm. Plus, high school starts earliest, which deprives adolescents of sleep as well. On the weekends, some adolescents try to make up for lost sleep by sleeping in, but this does not erase 5 days of partial sleep deprivation. Advocates have requested later school start times to help, but this is not done in most schools.

This study is about kids that are homeschooled. In this population, these kids can sleep in later, offsetting the daytime sleepiness from sleep deprivation as seen in public / private school kids. Also, kids that are homeschooled have a parent with them more often and thus may have better sleep hygiene than public / private school kids - meaning less TV / screen time in bed, less caffeine in evening, etc.

Study participants were surveyed about their sleep patterns and sleep hygiene via internet. Mean age of the sample was 13.6 years old. The results showed that kids in public / private school went to bed somewhat earlier on weekdays, but got up much earlier, resulting in 49 less minutes of sleep than homeschooled kids. Also, public/private school kids tended to sleep in more on weekends than homeschooled children. Using the National Sleep Foundation’s categories of “optimal sleep” (>9 hours) 28.2% of public/private school students obtained optimal sleep on weekday nights compared to 58.0% of homeschooled students. Public/private school kids tended to have "poorer" sleep hygiene than homeschooled kids.

The authors concluded that later school start times would allow private / public school kids to get more sleep.