Which other factors can affect focus & attention?

The following factors may adversely affect focus & attention:

• Sleep: both acute^[1] and chronic^[2] sleep deprivation can have negative effects on cognition, including focus & attention^[3]
• Chronic stress^[4]
• Infectious disease^[5]
• Depression^[6]
• Addiction and substance abuse^[7][8]
• Incomplete or unresolved tasks^{[9][10][11][12]}
• Rumination^[13]
• Lack of planning^[10]