Circadian pain patterns in human pain conditions - A systematic review.

Background: Chronobiology is the science of how physiological processes in the body follow a pattern of time. Pain has been shown to follow a circadian rhythm, with different types of pain having variable expression along this rhythm.

Objective: This article reviews the nature of diurnal variations in pain along with a discussion of the mechanisms of circadian rhythm of pain.

Different pain responses to chronic and acute pain in various ethnic/racial groups.

Aim: Our goal in this study was to review the similarities and differences among ethnic groups and their respective responses to acute and chronic clinically related and experimentally induced pain.

Method: In this review, the PUBMED and Google-Scholar databases were searched to analyze articles that have assessed the variations in both acute and chronic pain responses among different ethnic/racial groups.

Results: According to the results from 42 reviewed articles, significant differences exist among ethnic-racial groups for pain prevalence as well as responses to acute and chronic pain.