Abstract: The purpose of the study is to investi gate the effects of melatonin on enhancing immunity.2-month -old female Kunming mice were s elected in regulating immunity tests.And in the improving sleep tests 1-month -old male BALB /c mice w ere selected.Mice were divided into control,low -dose(0.5mg /kg.•bw)and high -dose(1.0mg /kg•bw)groups.Control group was given distilled water,low -dose and high -dose groups were g iven different melatonin doses.The results showed that,compared with control group,low dose melaton in could improve the thickness of tum escence toe by 22.3%(p <0.001),NK cell activity 62.2%(p <0.05)and levels of HC 50 17.1%(p <0.05),the cell’ s quantity of antibody formation(PFC)5.3%(p <0.05)and the carbon clearance indexα15.9%(p <0.05).It could also prolong the sleep time 23.4%(p <0.001)and improve the sleep rate 4times(p <0.01).High dose melatonin could improve the thickness of tumescence toe by 33.3%(p <0.001),prolong the sleep time 38.7%(p <0.001)and improve the sleep rate 3.5times(p <0.05).Conclusion:These results indivated that low dose melatonin had the function of enhancing immunity,while low and high dose melatonin could contribute to improve sleep quality.

Key words: melatonin, immunity, sleep, tardy a llergic reaction, iymphocyte proli feration, NK cell, carbon clearance, hemelysin