How is pre-sleep arousal defined?

Pre-sleep arousal can be cognitive or somatic.

• Cognitive pre-sleep arousal involves excessive thinking when trying to go to sleep. For example, replaying events of the waking day such as a heated argument or mistake at work could be classified as cognitive pre-sleep arousal. 
• Somatic or bodily pre-sleep arousal is any physical agitation within the body before bed. This could involve feeling muscle tension or jitteriness before sleep. Intense physical activity, like running or heavy weight lifting, might interfere with sleep if it is done too close before going to bed.