Objective To observe the clinical effect of acupuncture for delayed sleep-wake phase disorder（DSWPD）.Methods A total of 84 patients with DSWPD were randomized into an observation group（42 cases

2 cases dropped off） and a control group（42 cases

3 cases dropped off）. On the basis of sleep hygiene education

acupuncture was applied at Shenmai（BL 62）

Zhaohai（KI 6）

Hegu（LI 4）

Taichong（LR 3）

Zusanli（ST 36） and Sanyinjiao（SP 6） in the observation group

while placebo acupuncture was applied at the same acupoints in the control group. The treatment lasted for 8 weeks

once every other day

3 times a week in the 1st to 4th weeks; once every 3 days

2 times a week in the 5th to 8th weeks. Before and after treatment

the actigraphy（ACT） indexes of objective sleep（total time of stay in bed

total sleep time

sleep efficiency

the number of awakenings and the wake time after falling asleep） and plasma cortisol（CORT） level were observed; before and after treatment and in follow-up of 1

3 months after treatment

the scores of morningness-eveningness questionnaire（MEQ）

insomnia severity index（ISI）

fatigue severity scale（FSS） and Epworth sleepiness scale（ESS） were observed in the two groups. Results Compared before treatment

the total sleep time was prolonged

the sleep efficiency was improved

the number of awakenings was reduced

and the wake time after falling asleep was shortened after treatment in the observation group（P<0.01

P<0.05）

and those in the observation group after treatment were superior to the control group（P<0.01

P<0.05）. Compared before treatment

the MEQ scores after treatment in both groups and in the follow-up of 1

3 months after treatment in the observation group were increased（P<0.01）

and the MEQ score of each time point after treatment in the observation group was higher than the control group（P<0.01）. The scores of ISI

FSS and ESS after treatment

and the scores of ISI、ESS in follow-up of 1

3 months after treatment in the observation group were decreased compared with those before treatment（P<0.01

P<0.05）

and in the observation group

the scores of ISI

FSS and ESS of each time point after treatment were lower than those in the control group（P<0.01

P<0.05）. After treatment

the plasma CORT level in the observation group was decreased compared with that before treatment and that in the control group（P<0.01

P<0.05）.Conclusion Acupuncture can improve the sleep and wake phase of patients with DSWPD

improve sleep quality and daytime function

and its mechanism may be related to the down-regulation of plasma CORT level.