Arousal (noun)

1. The state of being awake and alert.
2. The physiological and psychological state of being primed for action, especially in response to a perceived threat or opportunity.
3. The state of sexual excitement.

Origin:

From old french arousal "rousing, waking", from latin arisere "to rise".

Examples:

1. The loud noise caused a sudden arousal from sleep.
2. The soldier experienced an arousal of adrenaline as the enemy approached.
3. Arousal can be measured by changes in heart rate and blood pressure.
4. He felt a strong arousal as he saw her.
5. Arousal can be physical or psychological.