30 Sep Nocturnal Asthma
Symptoms of asthma occur when the upper airway becomes inflamed and constricts to make breathing difficult. Although asthma affects people of all ages, it often starts in childhood and is more common in children than adults. Incidences of asthma are on the rise but exactly what causes asthma is still not entirely clear. Whether it is the result of environmental or genetic factors, what triggers asthma can be extremely variable between people and age groups. All asthmatics should be aware of the most common triggers; allergens (including mould), animal dander, strong odours, smoke, dust and dust mites, colds, flu and viruses, weather, exercise, reflux disease, foods, laughter and even particular medications. It is important for an individual to recognise what causes an asthma attack for them and take precautions to avoid exposure.
Often people with asthma can suffer from night time coughing and wheezing and have shortness of breath and chest tightness during the night which can highly disrupt sleep and lead to daytime tiredness and irritability. It is thought that sleep itself or circadian rhythm has an influence on promoting these night time disturbances, leading to the term Nocturnal Asthma, although exactly how is not entirely clear.
Throughout the night airway resistance increases regardless of whether you are asleep or not, although it is more predominant if you are asleep. In combination with increased airway resistance nocturnal asthma symptoms may result from or be exacerbated by decreased respiratory function during sleep. Hormone sections that follow a circadian pattern may also have a contributing affect.
Although it is obvious that the afore mentioned environmental triggers can provoke an attack, studies report that when allergen exposure occurs in the evening, the body is more susceptible to having a late phase response of grater severity than if occurred during the morning. Late phase asthmatic response is characterised by an increase in airway responsiveness, development of bronchial inflammation and a more prolonged period of airway obstruction.
There are also a number of other underlying factors which may also help to explain why night time seems to exacerbate asthma symptoms:
Increased mucus or sinusitis with asthma is quite common. Increased drainage from the sinuses can also trigger asthma in highly sensitive airways.
Internal Triggers relating to sleep are being investigated as research suggests that breathing tests in nocturnal asthma sufferers are worse four to six hours after falling asleep.
Reclining position may also predispose the body to nocturnal asthma problems. Many factors can cause this, such as accumulation of secretion in the airways (postnasal drip), increased blood volume in the lungs, decreased lung volumes and increased airway resistance.
Air Conditioning or breathing colder air at night may also cause loss of heat from the airways. Moisture loss and airway cooling have been implicated in nocturnal asthma and are also important triggers of exercise induced asthma.
Hormones that circulate in the blood have well-characterised circadian rhythms. Epinephrine levels and peak expiratory flow rates are lowest at about 04:00am while histamine levels peak at this time. Epinephrine helps to keep the muscle in the walls of the bronchi relaxed so the airways remains wide and also supresses the release of histamine. Histamine can cause mucus secretion and bronchospasm. The decrease of Epinephrine during the early hours before morning may predispose the body to nocturnal asthma during sleep.
In addition to modifications to lifestyle and self-directed disease management, most people with asthma use a combination of quick-fix and long-term medicinal remedies. There is no cure for nocturnal asthma but daily asthma medications, such as inhaled steroids, are effective at reducing inflammation and preventing nocturnal symptoms. Long-acting inhaled corticosteroids may also be of benefit. Avoidance of potential allergy triggers such as dust mites or feathers in a down blanket may also be helpful in preventing nocturnal asthma attacks, so make sure that the bedroom is clean and free of dust.
It is important to note that sleep disturbance or insomnia is sometimes a side effect of asthma medication. Also, there is some evidence that people with asthma are at greater risk of developing sleep apnoea, a condition in which breathing is briefly and repeatedly interrupted during sleep. It is always recommended to discuss any sleep and respiratory problems with a health care professional. According to type and severity of asthma a doctor can prescribe treatment to help resolve nocturnal asthma and/or further refer for sleep testing at a centre if sleep disturbances are persistent after cessation of asthma symptoms.
Story source and further reading:
National Sleep Foundation