Stress is physical, mental, or emotional strain or tension.
Tension is mental or emotional strain, suspense, anxiety, or excitement . Anxiety is a reaction to a real or imagined threat, a general feeling of uneasiness or dread. Stress is not a disease and is a normal part of everyone's life. The most frequent undesirable reaction is anxiety. Anxiety is often accompanied by twitching or trembling , muscle tension, headaches , sweating , irritability , fatigue , nightmares , memory problems, sexual impotence , sleeplessness , dry mouth, or difficulty swallowing .