If the structures partly or completely block the throat, air can't flow to the lungs at all. This is called hypopnea (decreased breathing) or apnea (meaning “no breathing”) for at least 10 seconds. The lungs aren't getting fresh air. So the brain tells the body to wake up just enough to tighten the muscles and unblock the air passage. With an audible gasp, breathing starts again. This process may be repeated over and over again during the night. This can make your sleep fragmented with lighter stages of sleep. You may not remember waking up many times during the night. But because of lighter sleep, you will most likely feel tired the next day. The lack of sleep and fresh air can also strain your lungs, heart, and other organs. This may lead to problems, such as high blood pressure, diabetes, changes in thinking, behavioral disorders, heart attack, or stroke.