According to the CDC, in 2002 there were an estimated 30.8 million people in the United States who had diagnoses of asthma during their lifetime.1 This widespread disorder can play havoc with a good night’s sleep, but with the right management, it can be minimized and good sleep restored.
ASTHMA AND SLEEP
Asthma is categorized by frequency of symptoms and by FEV1 and/or peak expiratory flow measurements. Daytime and nighttime symptoms are examined separately when classifying severity due to the fact that asthmatics have increased symptoms at night. A study involving 3,129 asthmatic patients revealed that 94% of nighttime complaints of dyspnea occurred between 10 pm and 7 am with the peak in symptoms occurring at 4 am.2
Many of the same physiologic changes that occur during sleep affect patients with asthma. There is a reduced response to chemical, mechanical, and cortical input during sleep that is magnified in REM sleep. The response to high CO2 and low O2 levels is blunted during sleep and is even more of a problem during REM sleep. There is reduced responsiveness in muscles of respiration to respiratory center output with a resultant decrease in minute ventilation due to reduced tidal volume. Airway resistance is higher and peak expiratory flow rates are lower in asthmatics compared to normal subjects. There is increased parasympathetic tone and increased bronchoconstriction during sleep.
In studies of asthma and sleep that looked at hormonal changes, researchers found that hormones follow a circadian cycle. Cortisol is a naturally occurring glucocorticoid—a steroid that inhibits inflammation in the body. Cortisol levels were at the lowest level at midnight in both normal and asthma patients. Histamine, one of the naturally occurring mediators involved in inflammation and bronchoconstriction, was found to be at its highest level at 4 am. Airway hyperresponsiveness (as measured by bronchial challenge) was also increased in the nighttime hours versus daytime.3 Likewise, response to the bronchodilator albuterol was decreased at 4 am as compared to 4 pm. Nocturnal asthma also is associated with gastroesophageal reflux disease (GERD). However, achieving improvement in symptoms of GERD is not clearly tied to improvements in nocturnal asthma control.4
Nocturnal asthma has a detrimental effect on quality of life. In a study of some 400 asthmatic children, 40% had nighttime sleep interruptions due to asthma symptoms during the previous 4 weeks. In addition, these sleep disturbances were linked to an increased number of missed school days, more severe asthma symptoms, and increased reliance on rescue medications. Moreover, the parents of these children had an increase in the number of absences from work.4 (A child who is home from school sick with asthma will generally translate into a parent who is at home from work to care for the child.) Research has also shown that nocturnal asthma has a detrimental effect on testing for intelligence, aptitude, and personality. Some 40 asthmatic students were tested for performance in intelligence, aptitude, and personality before and after a randomized, controlled treatment regime of either fluticasone (an inhaled steroid that reduces inflammation), salmeterol (a long-acting inhaled bronchodilator that relieves bronchospasm), or a combination of the two. The asthmatic students showed abnormalities in baseline testing compared to the control group, but each treatment group showed improvement in the concluding psychometric testing (as well as in pulmonary function test results), regardless of the treatment protocol used.4
POSSIBLE MECHANISMS FOR NOCTURNAL ASTHMA
Besides the presence of GERD and increased parasympathetic tone, nocturnal asthma may be linked to several other factors. This includes airway cooling due to lower ambient temperatures, and increased allergen exposure due to the use of fans at night and the fact that mattresses and pillows tend to harbor dust mites. Mucociliary transport tends to decrease during the night and coughing is suppressed, with the end result of increased airway secretions and subsequent irritation, decreased airflow, and increased work of breathing.3,4
TREATMENT OPTIONS FOR ASTHMA DURING SLEEP
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Controlling asthma symptoms is a key focus in the national asthma guidelines found in the National Asthma Education and Prevention Program (NAEPP).5 There are several strategies to controlling nocturnal asthma symptoms. The sleeping environment should be well ventilated with clean, dust-free, cool air with optimal humidity to minimize allergen exposure. Use of high-efficiency filtration systems also can reduce allergen exposure. Mattresses and pillows should be covered in dust mite-proof covers. Carpets should be removed, and use of fans at night should be minimized. Pets should not be allowed to sleep on the bed in order to reduce exposure to pet dander. Stuffed animals and plush toys should be removed or washed in hot water (>130 degrees F) to reduce dust mites.4,5 Cockroaches should be controlled and mold eliminated to remove these allergens from the environment. Appropriate use of long-acting bronchodilators, inhaled steroids, sustained-release theophylline, leukotriene modifiers, and anticholinergic medications can help relieve allergic response, inflammation, and bronchospasm. The NAEPP guidelines recommend treating GERD with appropriate medications and suggest elevating the head of the bed on 6- to 8-inch blocks to help relieve reflux and aspiration. The full range of asthma strategies are found in the NAEPP guidelines on the National Heart, Lung, and Blood Institute Web site.5 There are also asthmatic patients who suffer from OSA. If this is diagnosed, CPAP may be needed to provide appropriate care. Moreover, the addition of CPAP often aids in relief of nocturnal asthma due to the relief of some of the work of breathing, reduction in GERD, and the elimination of snoring with the associated irritation/inflammation of the laryngopharyngeal tissues.6
Sleep brings many mysterious and sometimes detrimental changes to the body, particularly in regard to breathing. Healthy individuals generally have no problems related to these changes, but they can result in serious consequences for patients suffering from asthma. In addition, fatigue plays a role in the well-being of these individuals, either as a cause for increased risk (as it relates to respiratory failure) or as a result of increased disease. For asthmatics, there are particular strategies to help provide quality sleep and relieve symptoms. Control of symptoms and adequate self-management are the top priority. Health care professionals frequently deal with asthma in conjunction with inherent sleep disorders such as OSA. Due to the added burden these pulmonary diseases place on the body, clinicians need to know and understand the impact of asthma on sleep. It is imperative to take time to study more on these topics and become well versed in the best treatment options to improve the quality of sleep and the quality of life for these patients.
Bill Pruitt, MBA, RRT, CPFT, AE-C, is a senior instructor in the Department of Cardiorespiratory Sciences, College of Allied Health Science, University of South Alabama in Mobile. He also works as a PRN therapist at Springhill Medical Center and at the Mobile Infirmary Medical Center. He has been in respiratory care since 1980 and has experience in many aspects of the profession, including staff therapist, home care therapist, clinical specialist, department manager, and department director, researcher, and educator. He has written and published numerous articles for respiratory and nursing publications and is an accomplished speaker. He can be reached at .
- Centers for Disease Control and Prevention. National Asthma Control Program. Available at: [removed]www.cdc.gov/asthma/program.htm[/removed]. Accessed May 22, 2007.
- Sutherland ER. Nocturnal asthma. J Allergy Clin Immunol. 2005;116:1179-86, quiz 1187.
- D’Ambrosio CM, Mohsenin V. Sleep in asthma. Clin Chest Med. 1998;19:127-37.
- Calhoun WJ. Nocturnal asthma. Chest. 2003;123(3 suppl):399-405.
- National Heart, Lung, and Blood Institute. National Asthma Education and Prevention Program Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. Available at: www.nhlbi.nih.gov/guidelines/asthma/asthgdln.htm. Accessed May 23, 2007.
- Kasasbeh A, Kasasbeh E, Krishnaswamy G. Potential mechanisms connecting asthma, esophageal reflux, and obesity/sleep apnea complex—a hypothetical review. Sleep Med Rev. 2007;11:47-58.