Predicting Response to Non-Medication Insomnia Treatment

Some insomnia researchers think that chronic insomnia is a disorder of the autonomic nervous system (ANS), the part of our body that controls processes that we generally are not able to consciously control - like heart rate, pupil dilation, etc. It is felt that insomniacs have an overactive ANS that makes it more difficult to sleep. One way to measure the activity of the ANS is by recording the variability of the heart rate. Specifically, the frequency of the heart rate variability has been correlated with ANS activity.

In the August edition of the Journal of Clinical Sleep Medicine, researchers have come up with a non-medication way of treating insomnia. This treatment stimulates the vestibular system, which is part of the inner ear that controls balance. In the current study, they hypothesized that heart rate variability could predict who might respond to vestibular system stimulation.

The researchers studied healthy people over two nights. They slept their normal amount on the first night. But on the second night, they made the subjects go to bed 4 hours earlier to simulate a sleep onset insomnia. Also, the subjects were randomly assigned to receive either one hour of vestibular stimulation or sham therapy on that second night before bed. The results showed that in those subjects who fell asleep faster on the second night with the vestibular treatment had different heart rate variabilities than those that did not respond to vestibular treatment. And this variability was most pronounced in subjects > 35 years old.

The study authors suggest that future research might focus on the relationship between the ANS and insomnia, and how to predict response to various insomnia therapies. This would allow sleep physicians to better treat the various types of insomnia patients - since some respond to medications and some do not. Right now, it's very difficult for us to tell who is going to respond - but the results of the current study are encouraging.

Urinary Leukotrienes and Pediatric Obstructive Sleep Apnea

Pediatric obstructive sleep apnea (OSA) is on the rise, especially as our children struggle more with obesity. Kids that have enlarged tonsils and/or adenoids are also at risk for OSA. Some researchers believe inflammation plays a role in OSA as well. There is a study in the Sleep Journal about leukotrienes, which are markers of inflammation. The study included 282 children aged 2 to 12 years old who snored regularly at least 4 nights per week. All of the children had sleep studies to check for OSA. On the morning after the sleep study, the researchers measured a specific leukotriene, aka LTE4, in their urine.

The results showed that the more severe the OSA (defined as mild, moderate, or severe), the higher the LTE4 levels. Also, urinary LTE4 levels were higher in the children with OSA that were overweight versus normal weight children with OSA. Finally, there was an association between enlarged adenoids / tonsils and OSA, but only for normal weight children.

The researchers theorized that the broken up sleep and low oxygen levels caused by OSA was linked with the elevated LTE4 levels - and this marker of inflammation was elevated even in mild OSA. However, they were unable to determine if the elevated LTE4 levels come before or after the children developed OSA. The researchers speculated that perhaps medications that block leukotrienes could be used in the management of pediatric OSA, such as in normal weight patients with milder cases.

Pregnancy, High Blood Pressure, and Sleep-Disordered Breathing

Pregnant women snore more and have more nasal congestion than non-pregnant women. And pregant women with high blood pressure (a.k.a. gestational HTN) or pre-eclampsia (a.k.a. gestational HTN with protein in the urine) have even more snoring and nasal congestion. Some studies have suggested that women with getstational HTN or pre-eclampsia have a high prevalence of obstructive sleep apnea (OSA).

In this month's Sleep Journal , there is an article about pregnant women with gestational HTN and OSA. Study participants were at least 18 years old during their first and only pregnancy and had gestational HTN or pre-eclampsia. Controls were matched for gestational age and had no high blood pressure or protein in the urine. Results showed that women with gestational HTN were more obese than controls. There was a higher frequnecy of self-reported regular snoring and nasal congestion in women with gestational HTN vs controls. The women with gestational HTN also reported lower sleep quality but there was no difference in daytime sleepiness between the two groups. Sleep studies showed that women with gestational HTN had less total sleep time, lower sleep efficiency, and a lower percentage of REM sleep than the controls. Finally, 50% of women with gestational HTN had OSA compared to 12% of pregnant women without gestational HTN.

The authors point out that the higher OSA frequency in the women with gestational HTN could be due to the higher obesity rates, as OSA and obesity go hand-in-hand. But these findings are important because even mild OSA can affect blood pressure in non-pregnant patients. And recent data have shown that short-term relief of mild OSA with CPAP can improve blood pressure in pre-eclamptic patients. Therefore, it is important to screen pregnant women with gestation HTN for snoring, sleep quality, and OSA.

Sleep Apnea and Dementia Risk in Women

In the August 10th edition of JAMA is a study about the relationship of obstructive sleep apnea (OSA) and dementia. Researchers believe that memory can be impaired by untreated OSA, but it's not clear if memory is affected by broken up sleep and/or oxygen level dips as a result of the OSA.

Researchers studied 298 women (average age ~82 years old) without dementia at the start of the study. All of them had a sleep study at the beginning of the study. Interestingly, 105 of them had OSA that was at least moderate in severity. The researchers than tested the women for dementia 5 years after their sleep study.

After adjusting for other variables, the results showed that 31% of the women without OSA and that 45% of the women with OSA developed some form of dementia 5 years after their sleep study. Also, the memory defects were associated with oxygen level dips rather than broken up sleep.

One question raised is if treating the OSA will reduce the risk of getting dementia. Also, will this finding extend to men? More studies are needed to answer those questions.

Fragmented Sleep and Memory

Researchers published a study at the end of July in the Proceedings of the National Academy of Sciences about the effect of sleep fragmentation and memory in mice. Studies have shown memory problems can occur when sleep is frequently disrupted. However, scientists are not sure if the memory problems are due to shorter total sleep time, poor sleep quality, reduction in a particular sleep stage (e.g. dream or REM sleep), or from the annoyance of being repetitively awaken.

In this study, the researchers used a new technique to isolate the effects of sleep fragmentation from overall sleep quality. The mice's brains were prodded awake every 60 seconds for one night, and this resulted in measurable memory problems. The interesting part is that the frequent awakenings did not reduce REM or deep sleep percentages, the total amount of sleep, or appear to cause the mice any stress.

The researchers suggest that new skills and information are committed to memory during sleep when our brains replay recently learned actions or sequences. The frequent awakenings interrupt that process such that the memories can be lost or compromised before they are stored.

Compression Stockings and Sleep Apnea

Chronic venous insufficency is a disorder of the leg veins that can result in fluid accumulation in the legs and ankle swelling. When patients with chronic venous insufficiency lay down at night to sleep, some of the fluid is redistributed to the other parts of the body, including the head and neck. This can cause swelling in the neck, which can increase risk of sleep apnea. In fact, one research group in Italy has shown that in patients with chronic venous insufficiency, OSA severity was linked to the amount of fluid being redistributed from the legs to the neck region overnight.

Compression stockings can be used to treat chronic venous insufficiency. Now, that same Italian research group has just completed another study about using compression stockings to treat OSA. Twelve non-obese patients with OSA and chronic venous insufficiency were randomly assigned to either wear compression stockings for one week or not (the control period). After the week, each patient did the opposite for another week - a.k.a. crossover trial design. The results showed that at the end of the compression stocking-wearing period, there was a 62% reduction in leg fluid volume compared to the control period. There was a 60% reduction in neck circumference. Finally, there was a 36% reduction in the severity of OSA, from 48.4 to 31.3.

These findings are exciting, as chronic venous insufficiency is common with OSA. The results raise some important questions as well. Does the effect persist if compression stockings are worn for longer periods of time? Will other treatments for chronic venous insufficiency also reduce OSA severity? Will the compression stockings work in obese patients, in contrast to the non-obese and relatively healthy patients in this study? Finally, will the use of compression stockings also reduce the clinical signs of OSA like daytime sleepiness?

Children, Sleep, and the Television

I saw this article in the journal Pediatrics. Researchers surveyed about 600 parents about their preschool children's sleep and sleep problems, their TV viewing habits, and the content of television shows. The more TV that children watched in the evening and the more violent content they watched during the day, the more likely they were to experience sleep problems. It did not matter whether the violent programs were animated or live-action, or whether the kids were watching the shows with their parents.

This makes sense to most people. When I watched the Wizard of Oz with my then five year old daughter, she had nightmares that night - my wife said, "Way to go, sleep doctor daddy!" What is even more interesting about this study is that most of the violent content watched was actually children's programming - but these shows were more appropriate for 7 - 12 year olds, rather than preschool age.

Another interesting point about the study was that about 8% of preschoolers with a bedroom TV were tired during the day, compared with only 1% without a TV in their bedroom.

I am a strong believer that kids, especially young ones, should not have electronic devices in their rooms - they make it hard for kids to fall and stay asleep. Also, do not let your preschool children watch scary television - even if you think they can handle it. Stick with shows that have a PG-Y rating.