Wright K P, Myers B L, Plenzler S C, Drake C L, Badia P
Sleep and Psychophysiology Research Laboratory, Department of Psychology, Bowling Green State University, Bowling Green, OH 43403, USA.
Brain Res. 2000 Aug 11;873(2):310-7. doi: 10.1016/s0006-8993(00)02557-9.
Caffeine and bright light effects on nighttime melatonin and temperature levels in women were tested during the luteal phase of the menstrual cycle (n=30) or the pseudo luteal phase for oral contraceptive users (n=32). Participants were randomly assigned to receive either bright (5000 lux) or dim room light (<88 lux) between 20:00 and 08:00 h under a modified constant routine protocol. Half the subjects in each lighting condition were administered either caffeine (100 mg) or placebo in a double-blind manner at 20:00, 23:00, 02:00 and 05:00 h. Results showed that the combination of bright light and caffeine enhanced nighttime temperature levels to a greater extent than did either caffeine or bright light alone. Both of the latter groups had higher temperature levels relative to the dim light placebo condition and the two groups did not differ. Temperature levels in the bright light caffeine condition were maintained at near peak circadian levels the entire night in the luteal and pseudo luteal phase. Melatonin levels were reduced throughout the duration of bright light exposure for all women. Caffeine reduced the onset of melatonin levels for women in the luteal phase, but it had little effect on melatonin levels for oral contraceptive users. The results for women in the luteal phase of the menstrual cycle are consistent with our previous findings in men. The results also suggest that oral contraceptives may alter the effects of caffeine on nighttime melatonin levels.
在月经周期的黄体期（n = 30）或口服避孕药使用者的假黄体期（n = 32），测试了咖啡因和强光对女性夜间褪黑素和体温水平的影响。参与者按照改良的固定日常方案，在20:00至08:00之间被随机分配接受强光（5000勒克斯）或暗光（<88勒克斯）。在每种光照条件下，一半的受试者在20:00、23:00、02:00和05:00以双盲方式服用咖啡因（100毫克）或安慰剂。结果显示，与单独使用咖啡因或强光相比，强光和咖啡因的组合在更大程度上提高了夜间体温水平。后两组相对于暗光安慰剂条件下的体温水平都更高，且两组之间没有差异。在黄体期和假黄体期，强光咖啡因条件下的体温水平在整个夜间都维持在接近昼夜节律峰值的水平。所有女性在强光照射期间褪黑素水平都降低。咖啡因缩短了黄体期女性褪黑素水平开始下降的时间，但对口服避孕药使用者的褪黑素水平影响不大。月经周期黄体期女性的结果与我们之前在男性中的研究结果一致。结果还表明，口服避孕药可能会改变咖啡因对夜间褪黑素水平的影响。
