• Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Causes of Fatigue Slideshow Pictures

Hay fever (allergic rhinitis)

Allergic rhinitis (hay fever) is a very common condition, affecting 17.6 million Americans annually. The symptoms of allergic rhinitis (sneezing, runny nose, nasal congestion, and itchy eyes) occur when an allergic individual is exposed to allergens. Allergens are tiny proteins that stimulate the allergic reaction. Common allergens include:

  • pollens from ragweed, trees, and grasses;
  • mold spores;
  • animal proteins; and
  • mites.

The best way to treat allergic rhinitis is to avoid the allergens. Skin testing is often performed to identify the allergens which cause allergic reactions in a given individual. Scientists now believe that the symptoms of allergic rhinitis, and even the skin testing results, can vary according to the time of day.

For sufferers of allergic rhinitis, the major symptoms of sneezing, runny nose, and stuffy nose are typically worse upon arising than during the middle of the activity span of a given day.


Asthma is a common breathing problem, affecting 16.1 million Americans. Asthma is a disease of the lung airways (bronchi). Narrowing of the openings of the airways (caused by spasm, swelling of the tissue lining, and/or mucus accumulation) can lead to shortness of breath, wheezing, or coughing.

Causes of asthma attacks include:

Asthma attacks (rapid worsening of symptoms) typically occur in episodes. Intervals between attacks can be days, weeks, or years. With severe asthma, attacks can occur daily. Scientists now believe that asthma attacks vary according to the time of day.

The occurrence of asthma attacks is not random during the day. Asthma symptoms are frequently worse at night (nocturnal) for a majority of asthma sufferers. A group of active asthma patients recorded the occurrence of acute asthma attacks, manifested by dyspnea (difficulty breathing) and wheezing, during a medication trial.

The incidence of asthma attacks was more than 100 times greater during nighttime sleep, especially around 4 a.m., than it was during the middle of the day.

Medically Reviewed by a Doctor on 6/18/2015

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