In some cases, modifying behavior and altering respiratory medications can alleviate sleep problems.

Sleep quality is affected when symptoms of a respiratory disorder manifest themselves soon before bedtime or during sleep. For many people, symptoms such as wheezing and coughing worsen from late evening to early morning. Scientists are not sure why this occurs, but one theory is that various internal rhythms such as the production of eosinophils may be responsible for the apparent circadian rhythmicity of respiratory symptoms.

Eosinophils are white blood cells that cause airway inflammation. They are produced at higher levels in early morning, but at lower levels by late afternoon.¹ The daily fluctuation seen in respiratory symptoms reflects the fluctuating level of inflammation caused by eosinophils.

Controlling respiratory symptoms is the key to improving sleep. Medication is sufficient to control symptoms in some people, but for others, medications alone do not control symptoms effectively. Lifestyle and presleep habits also can have an impact on respiratory symptoms.

Smoking, alcohol, and exercise
Some studies² suggest that smokers have more episodes of apnea and hypopnea during sleep than nonsmokers. Other studies³ show that the blood-oxygen level during sleep is lower in smokers than in nonsmokers. Lowered oxygen levels can increase the occurrence of apneas and hypopneas during sleep.

Alcohol is a central–nervous-system depressant. This depressive action lowers the tone of upper-airway muscles that normally would keep the upper airway open during sleep. When overly relaxed as a result of alcohol, the upper airway collapses and cuts off airflow. The cessation of breathing ultimately causes the person to awaken briefly to take some deep breaths. The arousal lasts only for a few seconds and the person quickly goes back to sleep. Once he or she is asleep, this process repeats. The repeated arousals fragment sleep and cause sleepiness the following day.

The airway normally constricts with exercise, but in some people, the constriction is excessive. Scientists are not fully sure why this occurs. Many researchers are looking into the effects of nitric oxide and vascular endothelial growth factors (VEGF).

Nitric oxide is a byproduct of cellular metabolism in the lungs. In times of irritation (due to allergens, for example), nitric oxide is overabundantly produced because of increased cellular growth. The excessive nitric oxide breaks down protective fluids lining the lung. This allows further irritation to lung tissue, which then swells, and the inflammation causes airway passages to narrow. Some people—for example, those with asthma—have higher-than-normal levels of nitric oxide. Exercise, for such people, further constricts an already narrowed airway.

VEGFs normally help repair injury to lung tissue. A faulty immune response can cause these factors to be produced in excess. Inflammation results, and the airway becomes constricted. The chronic narrowing that results from chronic inflammation due to VEGFs becomes apparent with exercise.

Stress and medication
Stress exacerbates symptoms of respiratory disorders. Production of white blood cells and interleukin is increased during times of stress. These agents cause inflammation and narrowing of the airways.

Another factor that can cause a person to struggle with poor sleep quality is, ironically, the use of respiratory medications.

Corticosteroids (such as prednisone) help reduce airway inflammation. These drugs can affect sleep by lessening the amount of rapid–eye-movement sleep. A sufficient amount of this stage of sleep is needed for a person to feel mentally restored.

Methylxanthines (such as theophylline) dilate airway passages by relaxing the smooth muscles. They appear to have no long-term effect on sleep stages. The short-term effects of methylxanthines, however, are increased arousals during sleep and a shortened sleep time.⁴ Initially, a person taken a methylxanthine may have more problems going to sleep and remaining asleep until drug tolerance has been established.

The b2-adrenergic agonists (such as albuterol) work by stimulating b2 receptors that cause the airway to dilate. The b2-adrenergic agonists appear to have no effect on sleep. These are the only common respiratory drugs that do not affect sleep.

Antihistamines (such as loratadine) reduce swelling of nasal tissues by blocking the inflammatory actions of histamine. Antihistamines also block the stimulatory action of the neurotransmitter choline. Because of their actions against choline, a side effect of antihistamines is sleepiness.

Anticholinergic medications (such as ipratropium bromide) inhibit the bronchoconstrictive actions of the neurotransmitter acetylcholine. These drugs can result in sleepiness because they block acetylcholine’s stimulatory effect.

Corrective actions
Some people become accustomed to having trouble going to sleep or having sleep interrupted because of respiratory symptoms, but nocturnal worsening of respiratory symptoms is not necessarily inevitable. Gaining better control over symptoms may be a matter of making lifestyle changes and changing presleep behaviors.

Patients should be advised not to smoke immediately before going to bed. Smoking can lower blood-oxygen levels and cause increased problems with apnea and hypopnea. Patients should not drink alcohol just before going to bed. Alcohol increases the likelihood of sleep apnea. They should not exercise strenuously before bedtime, since exercise can cause excessive narrowing of the airway. If exercise is part of their regular schedule, it should not occur within 6 hours of bedtime.

Patients should incorporate stress-reducing activities into prebedtime routines; these activities could include massage, a hot bath or shower, or listening to music. Reducing stress has been shown to lead to a reduction of inflammatory agents such as eosinophils.

Patients can also ask their physicians to prescribe different medication if problems with sleepiness or wakefulness remain. More recently developed drugs can help patients avoid undesired side effects on sleep while providing respiratory relief.

Regina Patrick, RPsgT, has worked in the sleep field for 17 years. She has been a member of the Association of Polysomnographic Technologists since 1987. She works for St. Vincent Medical Center in Toledo, Ohio.

References
1. Panzer SE, Dodge AM, Kelley EA, Jarjour NN. Circadian variation of sputum inflammatory cells in mild asthma. J Allergy Clin Immunol. 2003;111:308-312.
2. Wetter DW, Young TB, Bidwell TR, et al. Smoking as a risk factor for sleep-disordered breathing. Arch Intern Med. 1994;154:2219-2224.
3. Casasola GG, Alvarez-Sala JL, Marques JA, et al. Cigarette smoking behavior and respiratory alterations during sleep in a health population. Sleep and Breathing. 2002;6:19-24.
4. Roehrs T, Merlott L, Halpin D, et al. Effects of theophylline on nocturnal sleep and daytime sleepiness/alertness. Chest. 1995;108:382-387.