科学家想开发一种“大自然处方”

A new study,published Thursday in Frontiers in Psychology,attempted to answer that question by asking participants to spend time in a place that"brings a sense of contact with nature"for at least 10 minutes per outing,three times per week,over the course of eight weeks.The researchers found that participants who immersed themselves in a"nature experience"for at least 20 minutes per outing experienced a significant decrease in their levels of the stress hormone cortisol.

心理学前沿(Frontiers in Psychology)周四发表的一项新研究试图解决这个问题。研究人员要求研究参与者，每周三次每次至少10分钟置身于“感知大自然环境接触”状态下，为期八周。研究人员发现，那些每次至少20分钟沉浸在“大自然体验”中的参与者，压力荷尔蒙皮质醇水平明显下降。

The study's authors wrote that they envision ultimately developing a"nature prescription"—or"nature pill"—that health care providers can offer to their patients as a low-cost,preventive mental health treatment.(The"pill"is the time spent outside.)

论文作者说，他们最后想开发一种“大自然处方”(即“天然药丸”)。卫生保健机构可作为心理健康疾病低廉医治方法推荐给患者。(“药丸剂量”是暴躁在外部空间时间)

This research is the first step toward that goal,says MaryCarol R.Hunter,the study's lead author and an associate professor at the School for Environment and Sustainability at the University of Michigan.

该项研究主要作者、密歇根大学环境与可持续发展学院副教授MaryCarol R.Hunter说，我们的研究是迈向这一目标的第一步。

That's because the subject is tricky and expensive to study.Scientists don't yet know exactly which aspects of nature and green space—whether they're trees,grass,water,or plants—trigger the benefits of being outside.It's also difficult for them to design studies using the gold standard of a randomized clinical trial because neither scientists nor study participants are supposed to know which treatment or intervention the subject receives.In a study about exposure to nature,it's typically obvious to both the scientist and their subjects who's being sent to green spaces.

那是因为这门学科很难学，也很昂贵。科学家还不确切地知道自然和绿色空间的哪些方面-无论是树木，草地，水还是植物-都会引发外出的好处。他们也很难使用随机临床试验的金标准来设计研究，因为科学家和研究参与者都不应该知道受试者接受哪种治疗或干预。在一项关于暴露于自然的研究中，对于被送往绿地的科学家和他们的科目来说，这通常是显而易见的。

So Hunter and her colleagues tried an"adaptive management"approach instead.They let their 36 participants freely decide where,when,and how long they spent time in nature,provided they obeyed certain ground rules.They couldn't use phones or internet-connected devices to browse social media or the internet,and they couldn't make calls or read during their designated time outside.Their nature experience also couldn't include aerobic exercise.The researchers were collecting saliva samples that,in addition to cortisol,measured the hormone amylase,which can be influenced by physical activity.

所以，Hunter和她的同事尝试采用了一种“适应性管理”方法。他们让36名参与者自己决定置身于大自然位置、什么时候开始和停留时间。但应试者必须遵守某些基本规定，如不得使用手机或联网设备浏览社交媒体或互联网新闻，也不能在规定的置身于户外时间打电话或阅读书籍。大自然体验时间不进行任何有氧运动。研究人员事后收集了应试者唾液样本，除测量了皮质醇外，还测量了人体活动影响的激素淀粉酶。

"They could pick any place they wanted,"says Hunter,"but when they went to the place they actually had to feel some resonance to nature,feel connected to it.You could go sit next to one tree and just be with the tree,that could do it for you.The same person might go to a city park free of the noise of traffic."

Hunter说：“可选择去任何地方，但必须真正感受到与大自然产生共鸣，去感受大自然环境。坐在树旁边，和这树在一起，对健康是有好处的。城市人也可去公园，那里没有交通噪音。”

Peter James,an assistant professor in the department of population medicine at Harvard Medical School who has studied the link between nature and well-being,says the study's approach highlights the trade-off of letting participants shape the intervention based on their own interests.While it makes the research more feasible,it becomes difficult to know whether they stayed outdoors longer because of a personal inclination,like because they were having a great time—or some other factor unknown to the researchers.It's also then hard to know the characteristics of the participants'nature experience.

哈佛医学院(Harvard Medical School)公共医学系助理教授Peter James研究了自然与幸福之间的联系(link)。他说，为研究进行顺利，研究方法强调了尊重应试者兴趣的重要性。但是很难知道他们根据自己意愿会在户外待多久，若过得愉快也许更长，或存在研究人员尚不知道因素。因此很难知道参与者自然体验感受。

"This is a consistent problem in the literature,"says James."What is a nature experience?Is it looking at trees,grass,going on a hike,walking in an urban park?It's one of the vexing problems in this area of research."

James说：“这是在文学作品中存在的一致性问题。什么是大自然体验?是看树、看草、是远足、是在城市公园漫步吗?这是该研究领域最烦人问题之一。 ”

Hunter says that people's changing perception of nature is at the heart of this challenge.Venturing into a wilderness area might feel relaxing and restorative for one person,but terrifying for someone else,who'd much rather decompress in an urban park.Doctors who want to prescribe a nature experience to their patients shouldn't focus on a standard experience but rather encourage them to go where they feel most connected to the outdoors,Hunter says.

Hunter说，人们对大自然感受不同是这问题核心。有人进入荒野地区，感到心灵得到放松，精力得到恢复。但也有人感到恐惧，他们宁愿选择在城市公园里抒缓压力。Hunter说，医生若要给病人开大自然体验药方，就不应着眼于标准体验模式，而应该鼓励他们选择适合自己户外地方。

She also plans to release additional research based on the data collected in this study.In particular,Hunter wants to look at the self-reported information she gathered from participants about their mood,stress,and energy level to see if there's a correlation with the decrease in cortisol.

她还计划根据研究数据公布更多内容。Hunter尤其想看她收集的参与者撰写的自己情绪、压力和精力变化信息报告，了解一下这些变化是否与皮质醇下降有关。