What Is Nocturnal Asthma?

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Nocturnal asthma is the worsening of asthma symptoms at night. Your experience with it can vary over time. You may cough in your sleep or wake up frequently, or you may not notice such obvious symptoms at all—instead experiencing tiredness during the day due to sleep interruptions from nocturnal asthma. A number of factors increase the risk. If you're diagnosed, you might need an adjustment in your asthma treatment regimen to help reduce your nighttime symptoms.

Nocturnal Asthma Symptoms

Any type of asthma can be given an added diagnosis of nocturnal asthma. A key way to differentiate asthma that simply needs better management to avoid nighttime symptoms and nocturnal asthma is considering when symptoms occur.

Asthma that needs stricter treatment will result in symptoms any time of day, while nocturnal asthma's effects are worse only at night.

Nocturnal asthma can cause any of the following during sleep:

These symptoms can wake you up several times. Many people fall back asleep quickly and don't recall having had asthma symptoms or even waking up. If someone sleeps in the same room or bed as you, they might notice your coughing and wheezing if it's loud.

With nocturnal asthma, you might experience these issues several times per week or more.

The effects of nocturnal asthma can cause daytime sleepiness, even if you've spent enough time in bed during the night.

Low nighttime airflow into your lungs can also be an issue with nocturnal asthma, but you're unlikely to notice symptoms of this problem. It can contribute to daytime exhaustion and health complications, however.

Complications

Aside from daytime sleepiness, nocturnal asthma can also cause long-term effects. In particular, it can worsen your overall lung function, causing your asthma to progress.

Nocturnal asthma also increases the risk of health problems like heart disease and is associated with an increased risk of death. In fact, 70% of asthma-associated deaths and 80% of respiratory arrests caused by asthma occur during nocturnal hours.

No doubt, this is concerning. But your asthma prevention and treatment plans can be fine-tuned to reduce the effects of nocturnal asthma.

Causes

It's important to know that nocturnal asthma doesn't affect everyone who has asthma; in fact, many people who have asthma don't have any symptoms at night.

If you do have nocturnal asthma, a combination of the normal day and night fluctuations of the body and environmental triggers may be why.

Physical Changes

Your circadian rhythm, which is your internal body clock, regulates a 24-hour cycle of hormone activity and metabolism. The variations that occur during it have a major impact on sleep and lung function.

Factors that contribute to nocturnal asthma include:

  • Muscle control: When you are sleeping, your muscle control and strength are lower than when you're awake. Of course, we all breathe while sleeping, but the decreased muscle movement means shallow breathing and a reduction in lung volume (the total amount of air you take in). This can be problematic when you have asthma, as your lung function is already compromised.
  • Airway resistance: During sleep, your airways narrow slightly (bronchoconstriction). When you have asthma, bronchoconstriction is already a problem, so that small changes during sleep can worsen symptoms.
  • Inflammation: Your body's immune system and inflammation are a bit elevated at night. This is related to a natural decline in your steroid levels. Inflammation plays a major role in asthma, and a slight increase can worsen your symptoms at night.
  • Hormones: Hormonal changes during sleep change your metabolism and your rate and depth of breathing. Epinephrine, melatonin, and thyroid hormones all have such effects.
  • Sleep apnea: Sleep apnea is a condition characterized by pauses in breathing during sleep. Asthma and sleep apnea can worsen each other and compound symptoms.

Environmental Factors

Sometimes, your environment can worsen your asthma at night. For example, if you sleep in a room with asthma triggers, your asthma can worsen.

Try to be observant about whether your nocturnal asthma is worse in certain environments, such as when you sleep with the windows of your bedroom open, camp, or stay in a hotel.

Items like plants, pets, fabrics, and scents can worsen your asthma at night by triggering inflammation and bronchoconstriction as well.

Diagnosis

If your asthma symptoms clearly worsen at night, your doctor may diagnose you with nocturnal asthma in addition to your primary asthma diagnosis (e.g., allergic asthma) and start to consider therapeutic approaches.

Additionally, diagnostic tests can help identify nocturnal asthma. However, since daytime breathing tests might not be helpful—as respiratory effects are worse at night—you may be instructed to take some tests at home.

If there seems to be a serious problem with your breathing or your sleep, you might need a sleep study.

Approximately 10% of children who are diagnosed with asthma have symptoms of nocturnal asthma. And over 50% of adults living with asthma have this problem.

At-Home Diagnostic Tests

Before you take at-home breathing tests for evaluation of possible nocturnal asthma, your medical team will demonstrate how you should administer these tests on yourself.

You will need to take these tests right before you sleep and again in the morning right when you wake up to see whether your asthma has reduced your lung function overnight. Also, you need to keep track of your results in a notebook and bring it to your doctor.

  • Forced expiratory volume (FEV1): Your FEV1 is the amount of air you can exhale in one second with maximal effort. You can use a spirometer at home to measure your FEV1. With nocturnal asthma, this value can decrease by 15% or more between bedtime and morning when you wake up. 
  • Peak flow: Peak flow is the amount of air you can exhale; it isn't timed. With nocturnal asthma, your peak flow would be expected to decline by at least 15% between bedtime and morning. You can check this value at home with a peak flow meter.

The key is to breathe into the mouthpiece of these devices without letting any air out of your mouth or nose. You might be advised to repeat each measurement two or three times to make sure there isn't any error.

Sleep Study

If your nighttime breathing impairment is severe or if you have substantial fatigue during the day, your doctor might order a polysomnogram, a.k.a. a sleep study.

A diagnostic overnight sleep study tracks your muscle tone, sleep stages, oxygen levels, breathing rate, and can detect any pauses in your breathing that occur throughout the test.

Sometimes sleep studies are done at home, and some are done in a sleep laboratory.

Treatment

Medication is the key to managing nocturnal asthma, but that doesn't involve a specific drug to address the condition itself. Rather, it means that the proper timing of your asthma controller treatment is essential.

Lifestyle modifications can have a role in reducing the symptoms of nocturnal asthma. Avoiding asthma triggers can help prevent worsening asthma at night if environmental factors are contributing. And recent research shows that aerobic exercise can decrease the effects of nocturnal asthma as well.

If you have a sleep disorder, such as sleep apnea, treating that problem is vital for your health. Managing any health problems, especially those related to your breathing, may also help relieve symptoms of your nocturnal asthma.

Timing

Scheduling your asthma controller medications for optimal symptom control throughout the day and night is something you should be clear on and comply with.

Asthma controller medications include inhaled glucocorticoids, inhaled long-acting beta-agonist (LABA) bronchodilators, leukotrienes, and immunomodulators. Controllers work by preventing symptoms, so they aren't used at the last minute or when symptoms have already started.

Your doctor will prescribe your controller medications so that you will have better asthma control at the times when your symptoms are naturally at their worst—in the case of nocturnal asthma, this time is at night.

If you are unsure about when to take your medications or you feel your symptoms are not adequately controlled with your current regimen, speak with your doctor.

It may take some time for you and your doctor to gradually adjust your medication program as you track your symptoms.

A Word From Verywell

Nocturnal asthma can have an impact on your energy level during the day. It also increases the risk of long-term health problems, including worsening asthma at all times of the day. There are solutions, so it's vital that you talk to your doctor if you think you could be having more severe effects of your asthma at night.

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