Friday, February 5, 2016

Sleep and attention

This article discusses research in animals regarding the "yin and yang" of sleep and our ability to pay attention when awake. Probably seems fairly obvious to most of you, but it's interesting to see research findings supporting our clinical knowledge.

Wednesday, January 27, 2016

Fiber and saturated fat are associated with lighter sleep

Research studies have shown that reduced sleep amounts can impact food intake and weight. However there is relatively little information on how food intake could impact sleep. Apparently much of the work has focused on self-reported diet and self-reported sleep - in other words, not much has been done in a controlled, monitored environment.

This study attempted to assess whether sleep patterns were different after periods of controlled feeding versus ad libitum feeding - this means that one group was given exactly the same food. The other group was given $25 to buy whatever food they wanted. The controlled feeding was on days 1-4 and the ad libitum feeding on days 5 and 6. The participants sleep was monitored each night with a sleep study.

The results showed that ad libitum food intake was associated with a decrease in slow-wave (the deepest level) sleep and an increase in the time it takes to fall sleep. The greater intake of saturated fats and a lower intake of fiber were also associated with less deep sleep. Additionally increased intake of both sugar and non-sugar/non-fiber carbohydrates was associated with more arousals during sleep. The authors speculate whether a diet rich in fiber with reduced intake of sugars and other non-fiber carbohydrates maybe as useful tool to improve sleep depth and architecture in individuals with poor sleep.

These results are interesting, but the actual data shows what I consider to be small effects. The decrease in slow-wave sleep went from 29.3 minutes to 24.6 minutes per night. This may be statistically significant, but I wonder if this is really clinically significant. The time it took to fall asleep went from 16.9 minutes to 29.2 minutes - arguably a more noticeable change. Of note, there was no subjective evaluation of the patient's perceived sleep quality changes with the two different diets.

Thursday, January 14, 2016

No link between wake up time and income

I hadn't given this topic too much thought before, but I did find this article somewhat interesting. This study is based on a survey of individuals' wake up time and annual income. The results showed that the wake up time was no different in the highest income earners vs the lowest earners. The article goes on to say that the results of this study do not support the notion that the early bird gets the worm. I'm not so sure as other factors are not being considered in this situation.

Wednesday, December 30, 2015

Sleep deprivation and insulin

More research continues to be done on the effects of sleep deprivation on our metabolism. This article summarizes a small study looking at how acute sleep loss impacts insulin sensitivity. Researchers studied healthy, young adults without diabetes. They reduced their sleep time from 9 to 5 hours for five nights in a row - supposedly to simulate how little some may sleep during a workweek. After the 5 short nights, they let the participants sleep 9 hours a night for five more nights. The results showed that the subjects sensitivity to insulin decreased during the 5-hour sleep nights. This means that their bodies had to produce more insulin to keep their blood sugar under control. They didn't develop diabetes, but reduced insulin sensitivity is a precursor to diabetes. The next step will be to assess how less sleep affects older adults and adults with pre-diabetes / diabetes.

Wednesday, November 25, 2015

Sleep apnea and Meniere's Disease

Meniere's Disease involves the ear, and produces symptoms of hearing loss, tinnitus (ringing in the ears), and vertigo (a form of dizziness). Nausea and vomiting often accompany the vertigo. Meniere's Disease is usually treated with medications, but that does not always help. Some research has pointed to an association of poor sleep quality and Meniere's Disease. Obstructive sleep apnea (OSA) can result in poor sleep quality and could worsen Menierie's.

This small study looked at the effect of 6 months of CPAP therapy on Meniere's Disease. All 20 patients had failed medication management of Meniere's Disease. All had OSA diagnosed with a sleep study, and all used CPAP therapy only. They did not restart their Meniere's medications during this study. Results showed that CPAP therapy by itself reduced the impact of the vertigo and the low-frequency hearing loss associated with Meniere's disease.

The reason that treating OSA may help Meniere's is unknown. The study authors speculate that elimination of low oxygen levels when asleep may be the factor that improves the Meniere's. I also wonder if elimination of the snoring helps.

Wednesday, November 18, 2015

Pets and sleep

Lots of people sleep with their pets in their bed. This is fine unless it disrupts your sleep. This article discusses research at the Mayo Clinic showing that 18% of pet owners feel their pets disturb their sleep. The article goes on to discuss how you can get your pet out of your bed if it is bothering your sleep.

Wednesday, November 11, 2015

Control of dream sleep

The neurobiology of sleep is complicated - so many pathways in our brains seem to affect sleep and the different sleep stages. For example, the pons, a part of the brainstem, is thought to be the major part of the brain generating dream sleep. This article and abstract summarize elegant research demonstrating that a group of neurons in the medulla, which is below the pons, can generate signals that start dream sleep. The researchers postulate that these medullary neurons project up into the pons. This finding is interesting in that the medulla is responsbile for unconscious processes that regulate heart rate, blood pressure, and breathing, as well as other autonomic features. These research results may bolster the argument that dreams are not from the conscious brain, but more of an automatic process like breathing or heart rate. Unfortunately, these findings don't help us understand the function of dreaming any better than our current understanding.