Insufficient sleep is linked to the development of many chronic diseases.
By Susan B Trachman M.D. Posted December 11, 2023
Sleep disorders are on the rise globally.
Insufficient sleep puts you at risk for chronic disease, including dementia.
The glymphatic system clears toxic metabolites in your brain during deep sleep.
“Finish each day before you begin the next and interpose a solid wall of sleep between the two.” – Ralph Waldo Emerson
Sleep disorders affect people worldwide and are on the rise. Physicians know that good sleep is essential to good health. However, the issue is often overlooked in a busy primary care setting.
In a 2022 Gallup survey, only 32 percent of Americans said they got “excellent” or “very good” sleep; 35 percent described their sleep as “good.” In 2020, the latest year for which federal data are available, 14.5 percent of US adults had trouble falling asleep most days or every day in the past month, with women outnumbering men.
The causes of sleep disturbances are varied. Insomnia may be the primary problem, or it may be associated with other conditions. Treating the underlying cause can often resolve the insomnia, but sometimes it can be persistent. Some of the most common reasons for sleep problems include:
Stress: We are in the middle of the holiday season, which causes stress for some individuals. The additional responsibilities of buying gifts, sending cards, attending holiday functions, dealing with family, and sometimes long-distance travel can wreak havoc on even the best sleepers. Concerns about work, school, health, or finances can make your brain work overtime at night when it should be shutting down in preparation for sleep.
Travel or Work Schedule: Our 24-hour circadian rhythm is an internal clock and guides our sleep-wake cycle, metabolism, and internal body temperature. Any disruption to this internal clock can cause insomnia. Overseas travel, shift work varying from day to night, or even having a new baby who requires nighttime feeding can produce sleepless nights.
Poor Sleep Habits: These include behaviors such as excessive screen time during the hour or so before bed. Instead of helping your brain settle down, it promotes the opposite effect: activating the prefrontal cortex responsible for higher-level executive function. Irregular bedtimes, an uncomfortable bed or sleeping environment, or eating a heavy meal too late can lead to decreased sleep.
Medications: Many prescription and non-prescription medications can negatively affect sleep. Common allergy medications that contain decongestants like Sudafed can cause delayed sleep onset and restless sleep during the night.
Medical conditions: Conditions linked with insomnia include chronic pain, cancer, diabetes, heart disease, asthma, gastroesophageal reflux disease (GERD), overactive thyroid, Parkinson's disease, and Alzheimer's disease.
Sleep-related disorders: Sleep apnea causes you to stop breathing periodically throughout the night, interrupting your sleep. Restless legs syndrome causes unpleasant sensations in your legs and an almost irresistible desire to move them, which may prevent you from falling asleep.
Insufficient sleep is linked to the development of many chronic diseases and conditions, including type 2 diabetes, cardiovascular disease, obesity, and depression. There is excellent research interest in the role of sleep in the development of dementia. In 2021, researchers evaluated data from a cohort study of over 8000 participants spanning 30 years to investigate whether changes in sleep duration over this period were associated with dementia. They concluded short sleep duration in middle age is associated with an increased risk of later dementia.
Sleep Helps to Power Wash Your Brain
In the past ten years, scientists discovered a macroscopic waste clearance system called the glymphatic system in the brain. This stands for glial-dependent lymphatic transport. Glial cells provide physical and chemical support to nerve cells and maintain their environment. Located in the central and peripheral nervous systems, glial cells are sometimes called the "glue" of the nervous system. The glymphatic system removes proteins and metabolites from the central nervous system and supplies the brain with nutrients and chemicals that help modulate the connection between brain cells.
The glymphatic system is constantly active as a filtration device and is most active during a segment of sleep called non-REM but is disengaged during wakefulness. Non-REM is a part of the sleep cycle known as deep or slow-wave sleep. It is the type of sleep that allows you to wake up feeling refreshed, and it varies throughout your lifetime. Non-REM sleep peaks during puberty and slowly declines with age. One explanation for the neurodegeneration that occurs with Alzheimer’s and other dementias may partially involve the decreased duration of slow-wave sleep and, with it, less efficiency of the glymphatic system to detoxify unwanted accumulations of plaques and neurofibrillary tangles seen in those with Alzheimer’s disease.
Sleep abnormalities are highly prevalent in patients with neurodegenerative disease, often predating the onset of cognitive or neurological impairment. Alzheimer’s patients have a shorter total sleep time, increased awakening, and worse sleep efficiency, particularly slow wave sleep, compared to unaffected cohorts.
Strategies for Maximizing The Power of Your Glymphatic System
Consume fish oils such as omega-3 polyunsaturated fatty acids. This can be in the form of fatty fish, such as salmon, or as an over-the-counter supplement. These types of fatty acids improve glymphatic transport and decrease the accumulation of toxins.
Intermittent fasting. This consists of cycles of fasting followed by periods of eating. It can be achieved by an every-other-day fast (often less desirable) or by consuming all your nutrients during an eight-hour period, which tends to be more tolerable. This will increase glymphatic clearance.
Sleep position: Many people have a preferred sleep position. However, gravity affects the flow of blood and spinal fluid through the brain. Therefore, some sleep positions are more beneficial for clearing waste products. Research shows that glymphatic transport is most efficient if you sleep on your right side. However, most people do not know how much time they spend in various sleep positions as they change positions multiple times at night.
Alcohol Consumption: The effect of alcohol on the glymphatic system is unrelated to sleep or wakefulness. Long-term use of large quantities of alcohol dramatically reduced the efficiency of the glymphatic system in animal models. Surprisingly, small amounts of alcohol increased glymphatic clearance in some research studies.
Exercise: Glymphatic flow is accelerated by physical training. Aside from being good for your overall health, exercise has been documented to be a neuroprotective lifestyle choice for your brain.
Psychological Stress: Chronic psychological stress is a risk factor for Alzheimer’s disease and other neurodegenerative disorders. Living in a chronic state of stress accelerates the accumulation of unwanted proteins and toxins in your brain. Mindfulness meditation and other relaxation strategies are valuable techniques for lowering stress, along with cognitive behavioral therapy and medication if indicated.
Living in a stressful world can make getting a good night’s rest challenging. However, sleep is critical to good overall health, brain function, and mood. Depriving yourself of sleep can put you at risk for many chronic diseases. Sleep is not “downtime.” Your brain actually changes function while sleeping, and it is critical for removing unwanted proteins and toxins that can otherwise accumulate and lead to neurodegenerative disorders.
Dzierzewski, Joseph. “Sleep and Cognition in the Older Adult.” Sleep Med Clin, 2018, doi:10.1016/j.jsmc.2017.09.009.
Hablitz, Lauren M., et al. “Increased Glymphatic Influx Is Correlated with High EEG Delta Power and Low Heart Rate in Mice under Anesthesia.” Science Advances, no. 2, American Association for the Advancement of Science (AAAS), Feb. 2019.
Reddy, Oliver Cameron, and Ysbrand D. van der Werf. “The Sleeping Brain: Harnessing the Power of the Glymphatic System through Lifestyle Choices.” Brain Sciences, no. 11, MDPI AG, Nov. 2020, p. 868.