Photo Credit pollen image by asb from Fotolia.com. Allergies are a common cause of hives since an allergic reaction can trigger the immune system response that results in trapped fluid beneath the skin. An allergic reaction can occur due to something you ingested or were exposed to through the air.hoto Credit pollen image by asb from Fotolia.com. Allergies are a common cause of hives since an allergic reaction can trigger the immune system response that results in trapped fluid beneath the skin. An allergic reaction can occur due to something you ingested or were exposed to through the air.
There are likely to be other possible causes, so ask your doctor about your symptoms. 1  Various causes of drowsiness or sleepiness include: 2  Sleep debt. 3  Not getting enough sleep. 4  Shift work. 5  Jet lag. 6  Boredom. 7  Fatigue-see various causes of fatigue. 8  Sleepiness-see various causes of sleepiness.
Primary hypersomnia is thought to be caused by problems in the brain systems that control sleep and waking functions. Secondary hypersomnia is caused by conditions that cause fatigue. For example, sleep apnea can cause hypersomnia because patients have trouble breathing at night. Some medications can also cause hypersomnia. Frequent drug and alcohol use may trigger sleepiness during the day.