Anxiety is a feeling of fear, unease, and worry. The source of these symptoms is not always known.<unk>  can come from any event or thought that makes you feel frustrated, angry, or nervous.
Emotional<unk> : usually occurs in situations people consider difficult or challenging. Different people consider different situations to be<unk> ful.
Physical<unk> : refers to a physical reaction of the body to various triggers. The pain experienced after surgery is an example of physical<unk> . Physical<unk>  often leads to emotional<unk> , and emotional<unk>  often occurs as physical<unk>  (e.g., stomach cramps).
Stress
Opioid withdrawal
Homeostasis
Alcohol withdrawal
Opiate withdrawal
Sleep debt
Psychopathology
Doping 