Figure 4. Representative 12-hour light period hypnogram on the first day of post-orofacial pain for an individual SHAM rat (saline injection—Panel A) and an equivalent time-point in a rat subjected to orofacial pain (Freund’s adjuvant injection—Panel B). W represents a period of wakefulness. Note the marked fragmentation and reduced number of REM episodes in the orofacial pain animal.