RESUMO
<p><b>OBJECTIVE</b>To observe the effective mechanism of electroacupuncture for chronic fatigue syndrome (CFS).</p><p><b>METHODS</b>The dynamic detection of chronobiology was used to test the event-related potentials in 20 healthy subjects and 20 CFS patients. P3a and P3b latencies at 4 equidistant time points (8:00, 14:00, 20:00, 2:00) within 24 hours were collected and analyzed.</p><p><b>RESULTS</b>(1) Latency of P3a in CFS group was obviously prolonged at 14:00 compared to health group with statistical significance (P < 0.05), latency of P3b was decreased at 14:00 after electroacupuncture treatment with statistical significance compared to that of pre-treatment (P < 0.01). (2) There were obviously circadian rhythm in latency of P3a and P3b in health group (P < 0.05), which were not seen in CFS group (P > 0.05); the circadian rhythm latency of P3b restored after treatment (P < 0.05). (3) The latency acrophase of P3a and P3b pre-treatment obviously shifted backward compared to that of healthy subjects (P < 0.05), shifted forward after electroacupuncture treatment (P < 0.05).</p><p><b>CONCLUSION</b>The event-related potential circadian rhythms are lost in CFS patients. Electroacupuncture at Shenshu (BL 23) and Zusanli (ST 36) can regulate the circadian rhythm of P3a and P3b latency and improve the cognition of the patients in daytime.</p>