Dawson D, Encel N, Lushington K
Department of Obstetrics and Gynaecology, Queen Elizabeth Hospital University of Adelaide, South Australia.
Sleep. 1995 Jan;18(1):11-21. doi: 10.1093/sleep/18.1.11.
Chronic circadian disturbance is thought to cause many of the health and social problems reported by shift workers. In recent years, appropriately timed exposure to bright light and exogenous melatonin have been used to accelerate adaptation to phase shifts of the circadian system. In this study we compared adaptation to night shift in three groups of subjects. The first treatment group received timed exposure to bright light (4-7,000 lux between 2400 and 0400 hours on each of three night shifts). The second treatment group received exogenous melatonin by capsule (2 mg at 0800 hours then 1 mg at 1100 and 1400 hours). The placebo control groups received either dim red light at less than 50 lux or placebo (sucrose) in identical capsules at the same time. Results indicated that all groups shifted significantly from baseline. Using the dim-light melatonin onset as a circadian marker, the bright-light group shifted the furthest, whereas there was no significant difference between the melatonin and placebo groups. Sleep quality as determined by wrist actigraphy was most improved in the light-treatment group, although the melatonin group also showed significant improvements. Cognitive psychomotor performance was most improved in the light-treatment group and the melatonin group again showed little difference from the control group. Although melatonin was unable to increase the amount of the phase shift following transition to night shift, it is likely that the intermediate levels of improvement in sleep reflect the hypothermic effects of melatonin. By lowering core temperature across the sleep period, sleep may be enhanced. This improvement in sleep quality did not produce concomitant improvements in shift performance for the melatonin group. This suggests that the enhanced performance in the light-treatment group may reflect more direct "energizing" effects. On the basis of these results, bright light is clearly superior in its ability ot phase shift the circadian system and thereby improve sleep and performance. However, melatonin may permit shift workers to override the circadian system for short periods and avoid the potential toxicity due to overzealous manipulations of the circadian pacemaker. In rapidly rotating shift schedules, melatonin may be preferable because it would not require workers to reverse the large phase shift induced by light.
长期的昼夜节律紊乱被认为是导致轮班工作者所报告的许多健康和社会问题的原因。近年来，适时暴露于强光和外源性褪黑素已被用于加速对昼夜节律系统相位变化的适应。在本研究中，我们比较了三组受试者对夜班的适应情况。第一个治疗组在三个夜班的每晚24:00至04:00期间接受定时强光照射（4 - 7000勒克斯）。第二个治疗组通过胶囊服用外源性褪黑素（08:00服用2毫克，然后在11:00和14:00各服用1毫克）。安慰剂对照组在相同时间接受低于50勒克斯的昏暗红光或相同胶囊中的安慰剂（蔗糖）。结果表明，所有组均与基线有显著差异。以暗光褪黑素开始分泌时间作为昼夜节律标志物，强光组的相位变化最大，而褪黑素组和安慰剂组之间无显著差异。通过手腕活动记录仪测定，光照治疗组的睡眠质量改善最为明显，尽管褪黑素组也有显著改善。光照治疗组的认知心理运动表现改善最为明显，褪黑素组与对照组再次显示差异不大。尽管褪黑素在转为夜班后无法增加相位变化的幅度，但睡眠改善的中间水平可能反映了褪黑素的降温作用。通过在睡眠期间降低核心体温，睡眠可能会得到改善。褪黑素组睡眠质量的改善并未伴随轮班工作表现的相应改善。这表明光照治疗组表现的增强可能反映了更直接的“提神”效果。基于这些结果，强光在使昼夜节律系统发生相位变化从而改善睡眠和表现方面的能力显然更优越。然而，褪黑素可能使轮班工作者在短时间内超越昼夜节律系统，并避免因过度积极地操纵昼夜节律起搏器而产生的潜在毒性。在快速轮换的轮班时间表中，褪黑素可能更可取，因为它不需要工作者逆转由光照引起的大的相位变化。
