When people are confronted with unpleasant and potentially harmful stimuli such as foul odors or tastes, PET-scans show increased bloodflow in the amygdala. In these studies, the participants also reported moderate anxiety. This might indicate that anxiety is a protective mechanism designed to prevent the organism from engaging in potentially harmful behaviors.
Social anxiety varies in degree and severity. For some people, it is characterized by experiencing discomfort or awkwardness during physical social contact (e.g. embracing, shaking hands, etc.), while in other cases it can lead to a fear of interacting with unfamiliar people altogether. Those suffering from this condition may restrict their lifestyles to accommodate the anxiety, minimizing social interaction whenever possible. Social anxiety also forms a core aspect of certain personality disorders, including avoidant personality disorder.
Anxiety attacks that occur while sleeping, also called nocturnal panic attacks, occur less often than panic attacks during the daytime but affect about 40%-70% of those who suffer from daytime panic attacks. This symptom is also important because people who suffer from panic symptoms during sleep tend to have more respiratory distress associated with their panic. They also tend to experience more symptoms of depression and other psychiatric disorders compared to people who do not have panic attacks at night. Nocturnal panic attacks tend to cause sufferers to wake suddenly from sleep in a state of sudden fear or dread for no apparent reason. In contrast to people with sleep apnea and other sleep disorders, sufferers of nocturnal panic can have all the other symptoms of a panic attack. The duration of nocturnal panic attacks tends to be less than 10 minutes, but it can take much longer to fully calm down for those who experience them.
Occasional anxiety is an expected part of life. You might feel anxious when faced with a problem at work, before taking a test, or before making an important decision. But anxiety disorders involve more than temporary worry or fear. For a person with an anxiety disorder, the anxiety does not go away and can get worse over time. The symptoms can interfere with daily activities such as job performance, school work, and relationships.