Sleep’s Gift to Immunity – Monocytes, Macrophages, and Natural Killer Cells

“Sleep has been shown to be an important modulator of the immune response,” said Dr. Denise Sharon, MD, PhD, and Diplomate in Sleep Medicine. “Lack of sleep increases susceptibility to infection by decreasing immunity.” Dr. Sharon is a psychologist and physician and she now serves as Independent Consultant at Pomona Valley Medical Center’s Adult and Children Sleep Disorders Clinic.

Dr. Sharon previously served as Associate Professor of Medicine, Sleep Medicine Fellowship Faculty, and Assistant Clinical Professor of Pediatrics at the Tulane University School of Medicine in New Orleans, and also as director of the Comprehensive Sleep Medicine Center of the Gulf Coast.

“Sleep is a behavior,” Dr. Sharon explained, “and it is an important one for health.” Pointing to research by Besedovsky and others, “Sleep and immune function” in Pflugers Arch European Journal of Physiology, Dr. Sharon says, “Sleep supports the immune system through the initiation of an adaptive immune response.”

“There are two major types of immune response: innate and adaptive. Innate immunity is the first line of defense, the immediate generalized response to pathogens,” explained Dr. Sharon. “Adaptive or acquired immunity is an antigen-specific response and develops over time. The innate immune system cell types include monocytes, macrophages and dendritic cells. During sleep these undifferentiated immune cells peak in the peripheral blood and lymph nodes.”

“Growth hormone and prolactin are released during the same period of sleep and both enhance the proliferation and differentiation of the T cells, which are active in innate immunity. Natural killer cells–NK cells–are also affected by sleep,” she said, citing the research by Reis and others. “NK cells are part of the immune complement system whose activation is increased by sleep.”

“Sleep and immunity have a bidirectional relationship. The stimulation of the immune system triggers an inflammatory response that can induce an increase in sleep duration and intensity, but also sleep disruption. The enhanced sleep potentiates the immune system resulting in improved infection outcomes,” she said.

“Contrarily, sleep deprivation can lead to susceptibility to infections and if chronic to systemic low-grade inflammation,” she explained pointing to a 2019 study by Besedovsky and Lange, “The Sleep-Immune Crosstalk in Health and Disease” in Physiol Rev.

“There are huge numbers of people who are sleep deprived,” she said. “And it is a state in which negative emotion tends to prevail, like other strong need deprivation states.”

Clinical psychologist Dr. William Waters, long-time expert in the area of sleep would agree. “The whole country is sleep deprived,” he said in a previous interview. “You can’t do sleep deprivation research without feeling a little scared about traveling on the highway at night or early in the morning.”

Dr. Waters developed his interest in sleep during his years as Clinical Director at Louisiana State University throughout the 80s. An ABPP in clinical psychology with a strong psychophysiological background, Dr. Waters trained psychologists in sleep research and sleep medicine while Director and Full Professor at LSU. His first publication in the area of sleep was also in the 80s. He continues his interest at the Sleep Disorders Center at Ochsner Clinic in Baton Rouge.

“It’s not just sleep deprivation,” he said, “but the quality of sleep is very poor for many of those who actually do get enough sleep. For example, sleep apnea produces fragmented and light sleep that is not restorative, and causes the same functional decrements that are caused by sleep deprivation, including negative affect.”

Dr. Waters has worked in several areas of neuroscience research at the University of Missouri School of Medicine, LSU and the Pennington Biomedical Research Center. He holds fellowship positions in the American Academy of Sleep Medicine and he sits on the Board of Directors of the Louisiana Academy of Sleep Medicine. He is a Diplomate of the American Board of Sleep Medicine and the American Board of Professional Psychology.

Researchers have found that poor sleep patterns appear connected with a number of chronic illnesses, high stress hormones, hypertension, or a greater risk of diabetes and body mass.

“…And increased morbidity and increased mortality,” noted Dr. Sharon. “If we add intermittent hypoxemia, even mild, to the mix, the result is an inflammatory response that challenges the autoimmune system and contributes to plaque build-up.”

“Look for a middle-aged, overweight male or female,” said Dr. Waters, “and you are likely to find a problem with quality of sleep because they are likely to have sleep apnea. For psychologists, it is worth noting that sleep apnea will look a lot like depression,” he said.

As important as a full night of quality sleep is, the National Sleep Foundation’s data has revealed that 33.7 percent of responders said they did not get the amount of sleep they needed. And only 40 percent said they get a good night’s sleep every night or almost every night.

“The one thing that will reliably destroy sleep is stress,” Dr. Waters said. “No matter what the psychiatrists say, it is all continuous. If you want to take a point on the continuum and call it a disease you can. But stress–the psychophysiological responses–are aimed at getting you to deal with threat,” he said. “And then how likely are you to go to sleep?”

“Keep in mind that negative emotion is a stress response,” he said, “and therefore predictably disrupts sleep, delaying its onset, and making it light and interruptible. In other words, non-restorative.”

Helping a person get the rest and quality night sleep he or she needs was one of the first things that Dr. Sharon enjoyed in this specialty area. “Coming from psychiatry,” she said, “the first thing I liked about sleep medicine was instant gratification. The majority of our patients [obstructive sleep apnea, narcolepsy, restless leg syndrome] improve immediately after diagnosis and correct treatment with minimal if any side effects.”

“Sleep is the kind of area that clinical psychologists should be doing, it is just made for us,” Dr. Waters said. “We have a whole scientific discipline at our fingertips that is applicable.” He explained that the basic principles of behavior, applied to the treatment of sleep, is a perfect fit.

“Sleep hygiene and stimulus-control therapies are nothing more than applying what we know about sleep related behavior to make the person more likely to sleep,” he said. “Relaxation therapy is what we do to tone down activation. And remember that it is activation, particularly emotional activation, that causes insomnia and reduces the quality of sleep.”

Walter C. Buboltz, Jr. PhD, Professor, Director of Training Counseling Psychology, and his team of researchers at Louisiana Tech have worked to help unravel some of the complex issues in the area of sleep, for college students.

“Basically what we’re finding is people that have poor sleep quality tend to consume more food and weigh more over time,” said Dr. Buboltz, “Our hope eventually is to give them interventions or strategies to sleep better which would keep them healthier and decrease their weight.”

Dr. Janelle McDaniel, currently at University of Louisiana Monroe, and previously Assistant Professor and part of the team at Louisiana Tech, said, “It’s important to consider the interaction between different factors such as sleep and eating habits when thinking about wellness globally because treating one particular factor may not address underlying conditions.”

Dr. Buboltz and his team developed an intervention program for college students called the Step Program. “It’s basically training students to learn appropriate sleep habits, sleep hygiene and sleep education.”

Sleep hygiene, explained Dr. Buboltz, is “Doing things that promote sleep, like not drinking coffee past five, not working out at midnight or eating a lot of food before bed, but relaxing before going to sleep.”

Dr. Buboltz noted that their goal for these types of studies was learning about what’s appropriate. “Most people don’t know you’re supposed to sleep eight to nine hours a night. Most people don’t know about the amount of caffeine in food. Chocolate is actually worse for caffeine content than Coke! Colleges are bad about having intramural sports events at nine and ten o’clock at night and that prevents them from going to sleep.”

“We’re mainly focused on its effect on health,” Dr. Buboltz said.

With the overlap between major areas of psychology, psychophysiology, attention, emotion, Dr. William Waters finds this area to be perfect for those in psychology and the health promotion of patients. “The best clinician you can have is one with an integrated perspective,” he said.

Current research suggests that seven to nine hours of uninterrupted per night is necessary for the immune system to function optimally.

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