Sleep duration, efficiency and structure change in space
It’s hard to get a good night’s sleep in space. An evaluation of astronauts serving on the Mir space station found that they experienced shorter sleep durations, more wakefulness, and changes in the structure of their sleep cycles while in microgravity.
Researchers at Harvard College, Harvard Medical School, and NASA Ames Research Center studied the sleep patterns of four cosmonauts and one astronaut before, during and after spaceflight to conduct missions on the space station. Preliminary results show that they slept an average of only 5.7 hours in space, compared with 6.7 hours on Earth. They also spent significantly more time awake in bed, leading to a 17.7% reduction in sleep efficiency.
哈佛大学、哈佛医学院和 NASA 美国国家航空航天局埃姆斯研究中心的研究人员研究了4名宇航员和1名宇航员在空间站执行任务之前、期间和之后的睡眠模式。初步结果显示，他们在太空中的平均睡眠时间只有5.7小时，而在地球上是6.7小时。他们在床上醒着的时间也显著增加，导致睡眠效率降低了17.7% 。
In space their time in non-REM and REM sleep decreased by 14.1% and 25.8% respectively. On average it also took about 90 minutes after falling asleep for astronauts to reach their first episode of REM sleep in space, nearly 1.5 times longer than on Earth. In contrast, most sleep measures were stable across the inflight phase, with the exception of a decrease in the amount of time spent in bed and an increase in the length of time it took to fall asleep after going to bed.
在空间上，他们的非快速眼动睡眠和快速眼动睡眠时间分别减少了14.1% 和25.8% 。宇航员在太空中进入快速眼动睡眠平均需要90分钟，几乎是地球上的1.5倍。相比之下，大多数睡眠测量在整个飞行阶段都是稳定的，除了在床上花费的时间减少和睡觉后入睡时间增加。
“There were marked shifts in sleep architecture compared to baseline, and some of these evolved over the course of the mission,” said lead author Oliver Piltch, an undergraduate researcher at Harvard College. “Our findings were consistent with previous studies that focus on the issue of sleep continuity. We found significant decreases in sleep efficiency during spaceflight despite similar times in bed.”
“与基线相比，睡眠结构发生了明显的变化，其中一些变化是在整个任务过程中逐步形成的，”哈佛大学本科研究员、主要作者奥利弗 · 皮尔奇说。“我们的研究结果与之前关注睡眠连续性问题的研究一致。我们发现，在航天飞行期间，尽管在床上的时间相似，但睡眠效率明显下降。”
Piltch said scientists need to understand how sleep is affected by spaceflight to better equip astronauts for success on long-duration flights, like a trip to Mars or the Moon. He noted that the research also has implications for sleep on Earth.
“The significant sleep changes induced by the extreme environmental conditions of spaceflight can magnify and help reveal similar, though potentially less noticeable, changes that are induced by the more moderate conditions of Earth,” he said. “Our results support other studies indicating that sleep architecture can adapt to different environments. Also, the sleep deficits that our subjects were facing while working around the clock in a high-pressure environment provide further evidence for the danger of stress and shift-work schedules for humans anywhere.”
Statistical analyses of the research were guided by Erin Flynn-Evans, PhD, director of the NASA Fatigue Countermeasures Laboratory. The experiment was designed and led by Robert Stickgold, PhD, director of the Sleep and Cognition Lab at Beth Israel Deaconess Medical Center and professor of psychiatry at Harvard Medical School, alongside Dr. J. Allan Hobson, professor emeritus of psychiatry.
这项研究的统计分析是由美国宇航局疲劳对策实验室主任艾琳 · 弗林-埃文斯博士指导的。这项实验是由贝斯以色列女执事医疗中心睡眠与认知实验室主任，哈佛医学院精神病学教授 Robert Stickgold 博士和精神病学名誉教授 j. Allan Hobson 博士共同设计和领导的。