A research work studying the effects of high-fat diets in adult males leading to increased daytime sleep and increased obstructive sleep apnea — disrupted sleep due to loss of breathing for some time, which causes people to wake up many times during the night — was published in the journal Nutrients, in April 2016. The findings of the analysis, which included 1,800 Australian men, ranging between 35 to 80 years of age, suggested that the consumption of high-fat diet marked an increase of 78% in daytime sleepiness.

The survey showed that 41 percent men who took a high-fat diet reported daytime sleepiness, while 47 percent said they had trouble sleeping at night. It is important to note that high-fat intake’s correlation with sleep apnea was more significant in participants with high body mass index (BMI).

The data was collected over a period of one year, using food frequency questionnaires and electronic monitoring method of polysomnography for the confirmation of poor sleep at night, in previously undiagnosed patients. The analysis was conducted using ‘Men Androgen Inflammation Lifestyle Environment and Stress cohort’ study by the University of Adelaide’s Population Research and Outcome Studies unit in the School of Medicine and the Freemasons Foundation Centre for Men’s Health, Australia.

After adjusting the major factors that are associated with sleep such as smoking, alcohol intake, waist circumference, physical activity, medications, depression etc, 78 percent more chances of daytime sleepiness and three times more chances of sleep apnea were recorded in individuals who consumed fatty diets. Other macronutrients including carbohydrates and proteins were found to have no impact on sleep or the Apnea–Hypopnea Index (AHI). The association between fat intake and AHI was determined by taking BMI of the subjects.

The researchers involved in the study, emphasized on the working of human brain. According to them, the hypothalamus, the main unit of our brain, is regulated by the interplay of various hormones, most of which are strengthened by consuming different foods. In addition, the lead author of the study Yingting Cao, a doctoral candidate at the University of Adelaide, stated that the circadian rhythm, hormones and diet all work together to create the effects of increased sleepiness and disrupted sleep at night and said that the meal timing also effects these conditions. She added, “Extremely high-fat intake is not good for sleep. So the key message here is to eat healthy. But that’s easier to say than to do.”

The researchers believed that the findings of their study have the potential of paving way for other interventional studies, enabling people to achieve healthy weight loss while improving the quality of sleep. They affirmed that the working people would be greatly benefited by the outcomes of the research work put forward by this particular study, as increased daytime sleep negatively affects the working capacity of the workers in a professional work setting. The study was funded by the National Health and Medical Research Council (NHMRC) and the ResMed Foundation.

“Poor sleep and feeling sleepy during the day means you have less energy, but this in turn is known to increase people’s cravings for high-fat, high-carbohydrate foods, which is then associated with poor sleep outcomes. So the poor diet-and-sleep pattern can become a vicious cycle,” Ms Cao says.

National Library of Medicine, US, defines obstructive sleep apnea in adults as a condition in which the breathing pauses during sleep because the airways become narrowed or partly blocked. The condition majorly depends on factors including smaller lower jaw than the upper one, the shape of the mouth, large neck or collar size, large tongue that blocks the airways, large tonsils that also result in blockage of the airways and obesity.

Polysomnography is a diagnostic test for characterizing sleep disorders. The test helps for diagnosing possible sleep disorders, including obstructive sleep apnea (OSA). It is commonly recommended due to presence of the symptoms such as daytime sleepiness, loud snoring and restless sleep at night etc. It is performed, by placing electrodes on chin, scalp, and the outer edge of eyelids, whilst the patient is asleep. A monitor attached to chest records the heart rate and breathing patterns.

Moreover, the electrodes record signals when the person wakes up during sleep, while keeping eyes closed. The amount of time taken by the person to fall asleep is also recorded. Changes in the respiratory pattern along with cardiac rhythms are also observed by a specially-trained health professional. The movements during sleep are also constantly recorded with the help of video cameras.

The positive association of high-fat diets with hypersomnolence (increased daytime sleep), followed by obstructive sleep apnea in both humans and animals, was also reported by another study published in PubMed.