For those who are sensitive to pollen, dust mites and weeds, certain times of the year may make them feel under the weather. While a seasonal allergy attack is not a true illness, the body’s response to allergens may make the sufferer feel sick. Rather than allergies causing sleepiness, they cause fatigue, which may make the sufferer feel sleepy.

Seasonal Allergic Rhinitis

Seasonal allergies, or seasonal allergic rhinitis, is your body’s response when it comes into contact with substances it believes are harmful. You may respond to pollen -- grass and tree, pet dander or dust mites. When substances to which you are allergic enter your nose and throat, your immune system produces immunoglobulin, which releases huge amounts of chemicals into your nasal passages.

Symptoms

Shortly after your allergens enter your nose, mouth and throat, your nose gets runny or congested. You may sneeze and your eyes become watery, itchy and red. Because of your runny nose, you develop post-nasal drip and you may also get a sore throat and a dry cough. Your face, mouth and nose may itch. As your sinuses fill with mucus, you develop sinus pressure and pain and your eyelids and face around your eyes begins to swell. You get dark circles under your eyes – these are called “allergic shiners,” caused by the buildup of blood in the capillaries just under the skin. You become fatigued as your body continues to fight allergic substances.

Drug-Induced Sleepiness

Depending on the medications you take – antihistamines, antihistamine sprays, decongestants or prescription medications -- you may experience sleepiness. Antihistamine nasal sprays, which are just as effective as oral medications, can make you feel sleepy. Try not to drive or operate dangerous machinery while you are using these medications. If you take a high dose of a prescription antihistamine, you may become sleepy as well, writes the Harvard Medical School website.

Additional Treatments

Other non-medication treatments include avoiding substances to which you know you are allergic 2. If you cannot avoid going outside, keep your car windows rolled shut and use your air conditioning. Keep your house windows closed and use your home’s air conditioning for cool air. Ask your doctor about immunotherapy shots. While the therapeutic benefit takes several years to build, if you get your shots every week, within five years you may be able to stop taking oral and nasal medications.