Since we spend about a third of our lives sleeping, it follows that something that takes up so much of our time must be important to our health (1)! It is a matter of concern then, that many people do not get the sleep their bodies need to function at their best. 70% of American adults do not get sufficient sleep at least one night per month, and 11% report insufficient sleep every night (2). In fact, insomnia is the most prevalent sleep disorder among adults, with an estimated 10% of Americans suffering from chronic insomnia (2). To work toward healthy sleep habits and fight against insomnia, we must understand the role sleep plays in our lives, the impacts of poor sleep, and the importance of focusing on proper sleep hygiene.
What causes insomnia?
Insomnia is a condition that causes difficulty falling asleep, staying asleep, waking early, or not feeling rested after a night of sleep (4). Many individuals experience these symptoms at one point or another, but this condition becomes chronic when these symptoms persist at least three nights per week for three months or longer (3). Many factors can cause insomnia, including (4):
Travel or work schedules
Poor sleeping habits
Mental health problems, such as anxiety or depression
Medical conditions such as chronic pain, cancer, diabetes, or asthma
Caffeine, nicotine, and alcohol
Hormonal fluctuations due to menstruation and pregnancy
Gastrointestinal disturbances (intestinal permeability, dysbiosis, food sensitivities, etc.)
Various autoimmune or infectious inflammatory conditions
Environmental toxic exposures
Why is sleep so important?
Sleep affects almost every area of the body, so good sleep is crucial to optimizing overall health and well-being (5). First and foremost, sleep has huge restorative benefits for the brain. While we sleep, our brains sort and store memories, determining which information should be stored for the long term and which is expendable (6, 7). Quality sleep also keeps the brain functioning well, enabling sufficient attention and focus, sound reasoning, and efficient problem-solving skills (6). And, since our brain is a part of the nervous system (which is in charge of our body’s quick response system), good sleep even helps reflexes and response time, helping us avoid accidents (3, 6).
While the link between quality sleep and the many benefits above has long been observed, the reason for it has not. Scientists have recently uncovered that sleep helps to clean the brain through what they call the “glymphatic system”, a partnership between the brain’s glial cells and lymphatic system (6). During our day-to-day functioning, our bodies and brains produce byproducts such as beta-amyloids that end up in our brain and spinal (cerebrospinal) fluid that can become toxic if left to accumulate. To combat this, the sleeping brain signals glial cells to adjust its regulation of cerebrospinal fluid to drastically increase fluid. The body then uses the lymphatic system (made up primarily of lymph nodes, vessels, and fluid, as well as the tonsils, adenoids, spleen, and thymus) to thoroughly circulate cerebrospinal fluid through the lymphatic system, filtering out waste and toxins that have built up during the day. Not only does this lead to a healthier brain and better day-to-day functioning, but it may also help prevent Alzheimer’s disease since Alzheimer’s is linked to a buildup of beta-amyloid (6).