Objective To evaluate the influence of superficial needling on electroencephalogram(EEG)in patients with insomnia by using nonlinear kinetics measure.Methods Six patients(3 male and 3 female)suffering from insomnia for more than a month were recruited in the present study.EEG data before and during superficial acupuncture stimulation of Shangen point(the midpoint between the bilateral inner canthus)was recorded using an electroencephalograph for analyzing the correlation dimensionality(D 2)and approximate entropy(ApEn)of different cerebral regions.Results During superficial needling

the D 2 data of the right-forehead(Fp 2)

anterior area of the left temple(F 7)and the anterior region of the right temple(F 8)were significantly increased(P<0.05)

and ApEn data at the right anterior forehead(Fp 2)

left occipital region(O 1)

and F 8 region markedly decreased relevant to pre-acupuncture(P<0.05).Both paring test and trend analysis of D 2 data showed no significant changes.Only an obvious increase of D 2 was found in the Fp 2 region

suggesting a coherence of EEG activities in stability and synchronization during acupuncture treatment.Clustering analysis of D 2 data of various cerebral regions displayed a relatively concentrated tendency

particularly in the Fp 2

the right forehead(F 4)and F 8 regions.Factor analysis of ApEn data showed a significant change in Fp 2

F 8

O 1 and right occipital(O 2)regions.It suggests that during superficial needling stimulation of Shangen point

the EEG signals were lowered in complexity

and improved in synchronization

stabilization and ordering

favoring sleep at last.Conclusion Superficial needling of Shangen point can make the EEG signals synchronized in insomnia patients

suggesting an improvement of sleeping.