Pain tolerance is higher during daylight waking hours and lower at night, particularly between 2:00 AM and 5:00 AM.

“Our ability to tolerate pain changes dramatically across the 24-hour cycle, and as you can imagine, it's during the daylight waking hours that we are better able to tolerate, we are more resilient to pain, and we are better able to experience pleasure. At night, our threshold for pain is much lower. In other words, the amount of mechanical or chemical or thermal, meaning temperature stimuli that can evoke a pain response and how we would rate that response is much lower at night, and in particular, in the hours between 2:00 AM and 5:00 AM if you're on a kind of standard circadian schedule.”