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.

Deep sleep circuit in the brain

There are 4 different sleep stages that humans cycle through at night. Deep sleep is one of those stages, and is typically seen in the first half of the night, at least in adults. Sleep researchers do not know exactly how deep sleep is produced, but it's thought to involve the neurotransmitter GABA, which stands for gamma-aminobutyric acid.

Here is a report of a study involving stimulation of a deep part of the brain (the brainstem) that turns on deep sleep. The technique used to stimulate this area of the brain is different than other methods involving electrical stimulation of the cells in the brainstem felt to be responsible for deep sleep. With electrical stimulation, the problem is that the electrode stimulates everything it touches, including surrounding areas it did not come into contact with. As stated in the article, electrically stimulating cells was like using a sledgehammer, when what was needed was a scalpel. In this study, researchers inserted a harmless virus that incorporated itself precisely into the very cells the researchers were trying to study. The cells were then remotely "turned on" and the animals went right into deep sleep.

This is exciting research as it points to the possibility of developing therapies that enhance deep sleep by targeting only certain brain areas. Hopefully this will lead to treatments with more specific modes of action and less side effects.

Kids can sleep right through a fire alarm

Here is a video story about how kids can sleep through a fire alarm. Most parents know that kids sleep deeply. In this video story, the reporter set up an experiment demonstrating that three young boys slept right through the ear-piercing fire alarm in their home. But there is hope - one company is trying to improve the fire alarm but changing the noise it produces - instead of the beeping, it will be the parents voice telling the kids to get up.

Older age people may have memory problems from lack of deep sleep

This article discusses research about our aging brain, sleep quality, and memory. As we age, there is a reduction in volume in a part of our brain behind the middle of our forehead - the medial pre-frontal cortex (PFC). Sleep researchers think this area helps generate the deepest levels of sleep. As we age, the amount of deep sleep is reduced gradually. Many older people have little deep sleep. In this study, the researchers think that the older people who had less deep sleep than younger people, had reduced ability to remember new things. They think this effect is not so much about the volume reduction in the PFC, and more about the loss of deep sleep. Unfortunately, not much can be done to increase the level of deep sleep, whether you are old or young. Some medications have been shown to mildly increase deep sleep levels. Some researchers are apparently working with electrical stimulation of the brain - sounds interesting but I don't know more about it.

Acupuncture may increase deep sleep

This article discusses research showing that acupuncture may increase deep sleep. I have heard from some patients and friends anecdotally, acupuncture has helped their insomnia.

Deep Sleep, High Blood Pressure, and Elderly Men

There is an abstract in the journal Hypertension from August 2011 about the relationship between sleep stages and development of high blood pressure (a.k.a. HTN). There are three stages of sleep - light non-REM sleep, deep sleep, and REM (a.k.a. dream) sleep. Researchers studied 784 men greater than 64 years old who did not have HTN with an in-home sleep study. After a mean follow up of 3.4 years, 243 developed HTN. Analyses of the results demonstrated that developing HTN was associated with low oxygen levels, increased light non-REM sleep, and decreased deep sleep. After adjusting for age, nonwhite race, study site, and body mass index, only deep sleep was associated with developing HTN. The association was not reduced even after accounting for sleep duration, sleep fragmentation, and severity of sleep-disordered breathing (e.g. obstructive sleep apnea).

The researchers concluded that reduced deep sleep may contribute to adverse blood pressure in men. Unfortunately, the percentage of sleep that is deep sleep normally reduces with age in men and women. At the current moment, there is not a reliable way to increase deep sleep percentage without sleep deprivation or using medications.