Under Perens' definition, open source describes a broad general type of software license that makes source code available to the general public with relaxed or non-existent copyright restrictions.
1 Illnesses such as the flu or colds. Home treatment of your flu and cold symptoms usually will relieve lightheadedness. 2  Vomiting, diarrhea, fevers, and other illnesses that cause dehydration.  Very deep or rapid breathing (hyperventilation).
Photo Credit George Doyle/Stockbyte/Getty Images. If a person experiences a drop in blood pressure, fever, diarrhea, loss of hydration from vomiting or dizziness, lightheadedness can occur. Further, if the brain does not receive enough blood, it can cause lightheadedness as well.eart Attack. Heart attack is one of the more serious conditions that cause lightheadedness. During a heart attack, oxygen is prevented from getting to the heart and the rest of the body when blood vessels are blocked, causing the head to feel light and weightless.