By Brandon R. Peters, M.D.
It is an unusual thought, and one that is meant to be a little provocative. In a culture obsessed with both appearance and health, could there be an unlikely association between the two? Is it possible that your nose might not make you look fat, but could it actually make you become fat? In considering the matter, there is much to learn about the relationship between the body and its function as well as the role of quality sleep in proper metabolism.
In contemplating weight gain, the nose seems like an improbable culprit. Most people would far more likely blame the mouth for waistline woes. Nevertheless, the nose may indeed have a part to play. There is an inseparable relationship between each component of our body's anatomy and resulting function. It is a system designed to rely on each part, in a balance called homeostasis. When even a small piece of the whole functions poorly, the entirety faces consequences.
The nose is a surprisingly complex organ. Certainly the primary role is in breathing. Air is drawn in and with great speed becomes filtered, humidified and warmed by tissues called turbinates that line the nasal passage. Allergens detected in the environment may elicit an immune response. Smells may be perceived, even contributing to the taste of food. Moreover, in an oddball bit of trivia, the nose actually goes through something called the nasal cycle. Rather than breathing through both sides of the nose equally, one side will predominate while the other takes a break. Then, gradually over hours, the more open side will switch.
The nose has an extremely important role in normal breathing. In fact, humans are meant to be obligate nasal breathers, meaning that in normal circumstances we should breathe exclusively through our noses. It is only when breathing through the nose is difficult that the body switches to mouth breathing, and this can introduce a new set of problems. Obstruction of the nose may occur due to a cold or allergies, often with associated enlargement of the turbinates that can block the passage. In addition, the nasal septum -- the cartilage that lies at the midline and separates each side of the nose -- may be displaced or deviated. These problems may compel someone to chronically breathe through the mouth.
In popular culture, mouth breathing carries a connotation of someone who may be dull, with a vacant stare, and even drooling. Though this generally is not accurate, it also does not fully recognize the seriousness of the issue. People who consistently breathe through the mouth gradually develop a relaxation of the muscles of the jaw. Without this tension, especially when it starts in childhood, the anatomy of the face may change as development proceeds. The face can become more elongated. With decreased air passing through the nose, the tissues lining the upper airway may also relax, becoming more floppy and prone to collapse.
The combination of an obstructed nose and a more collapsible airway may lead to snoring and even obstructive sleep apnea. When breathing is interrupted during sleep, awakenings may occur as a result to reopen the airway. Sleep becomes fragmented with repeated transitions from deep to lighter stages of sleep, or even wakefulness. Sleep apnea may also lead to important long-term health consequences, including: high blood pressure, diabetes, depression, heart attack and stroke. It may also contribute to weight gain.
It is well understood that inadequate sleep can cause problems with metabolism. In both children and adults, sleep deprivation has been linked to weight gain. In 2002, a study of 1.1 million people found that higher body mass indexes (BMI) were more likely in people who slept less than seven to eight hours. Another study, from Wisconsin in 2004, found that the increase in BMI was proportional to the amount of decreased sleep, with those sleeping the least weighing the most. In a compelling study from 2005, short sleep duration at age 30 months predicted the later development of obesity at seven years, suggesting there may be permanent damage to the hypothalamus, a part of the brain that regulates energy expenditure. This complex interplay is likely additionally dependent on hormones that regulate hunger and appetite, known as ghrelin and leptin. Inadequate sleep, including poor quality sleep, may predispose to these weighty consequences.
Therefore, the nose may indeed have an unexpected role in weight gain. Disrupted breathing through the nose may lead to fragmented sleep that, in turn, affects the control of metabolism. These changes may start in childhood and evolve throughout one's life. Though the contributing causes of weight gain are multifactorial -- and admittedly more dependent on caloric intake, exercise, genes and cultural influences -- it may not be unreasonable to reserve a place in the discussion for the nose and, in turn, sleep.
For those who have difficulty breathing through the nose, especially when it affects sleep through snoring or apnea, it is imperative to seek appropriate evaluation by a specialist. Proper treatment may greatly improve your quality of life and make it possible to avoid some rather unexpected effects.
Sources:
Prinz, P. "Sleep, Appetite, and Obesity -- What is the link?" Public Library of Science and Medicine. December 2004. 1:186-188.
Spiegel, K. "Impact of sleep debt on metabolic and endocrine function." The Lancet. October 23, 1999. 354:1435-1439.
Spiegel, K. et al. "Brief Communication: Sleep Curtailment in Healthy Young Men is Associated with Decreased Leptin Levels, Elevated Ghrelin Levels, and Increased Hunger and Appetite." Annals of Internal Medicine. December 7, 2004. 141:846-851.
Taheri, S. et al. "Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index (BMI). Sleep. 2004. 27:146-147.
Taheri, S. "Sleep and metabolism: Bringing pieces of the jigsaw together." Sleep Medicine Reviews. 2007. 11:159-162.
Vorona, R. et al. "Overweight and Obese Patients in a Primary Care Population Report Less Sleep Than Patients With a Normal Body Mass Index." Archives of Internal Medicine. January 10, 2005. 165:25-30.
Brandon R. Peters, M.D., is the writer on sleep for About.com, a neurology-trained sleep medicine specialist in Novato, Calif., and consulting assistant professor at the Stanford Center for Sleep Sciences and Medicine. This Center is the birthplace of sleep medicine and includes research, clinical, and educational programs that have advanced the field and improved patient care for decades. To learn more, visit us at: sleep.stanford.edu.
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