Hormones

• Those with an abnormal level of hormones are more prone to having cluster headaches. Neurotransmitters, such as serotonin, have been abnormal during the headaches as well.
  
  

Smoking

• Cluster headaches occur more in smokers than non-smokers, according to Mayo Clinic.
  
  

Genetics

• Cluster headaches are typically genetic, being passed down from family member to family member.
  
  

Gender

• According to Mayo Clinic, men are more prone to developing cluster headaches than women.
  
  

Race

• African Americans are more prone to developing cluster headaches than Caucasians, although the reason for this is unknown.