Clinical Depression - 英语听力.mp3

[00:00.10]From VOA Learning English,
[00:03.52]this is the Health Report.
[00:05.29]Some colors that people see
[00:08.75]late at night could cause signs
[00:11.56]of the condition mental health experts call
[00:15.18]clinical depression.
[00:16.87]That was the finding of a study
[00:20.16]that builds on earlier study findings.
[00:23.03]They show that individuals
[00:26.08]who live or work in low levels of light overnight
[00:31.00]can develop clinical depression.
[00:33.51]Doctors use the words clinical depression
[00:37.67]to describe severe form of depression.
[00:41.80]Signs may include loss of interest
[00:45.22]or pleasure in most activities,
[00:47.51]low energy levels and thoughts of death or suicide.
[00:53.04]In the new study,
[00:55.46]American investigators designed an experiment
[00:59.58]that exposed hamsters to different colors.
[01:03.06]The researchers chose hamsters
[01:06.36]because they are nocturnal,
[01:08.42]which means they sleep during the day
[01:11.35]and are active at night.
[01:13.81]The animals were separated into 4 groups.
[01:18.60]One group of hamsters was kept in the dark
[01:22.81]during their nighttime period.
[01:25.38]Another group was placed in foldable blue light,
[01:30.15]a third group slept in foldable white light.
[01:34.28]While a fourth was put in foldable red light.
[01:38.99]After four weeks, the researchers noted
[01:43.76]how much sugary water the hamsters drank.
[01:47.08]They found that the more depressed animals
[01:51.19]drank the least amount of water.
[01:54.00]Randy Nelson heads the Department of Neuroscience
[01:58.77]at Ohio State University.
[02:01.53]He says animals that slept in blue and white light
[02:06.36]appeared to be the most depressed.
[02:09.62]"What we saw is these animals didn't show
[02:12.24]any sleep disruptions at all
[02:13.64]but they did have mucked up circadian clock genes
[02:17.42]and they did show depressive phenotypes
[02:22.05]whereas if they were in the dim red light, they did not."
[02:24.71]Randy Nelson notes
[02:26.31]that photosensitive cells in the retina,
[02:29.53]have little to do with eyesight.
[02:32.65]He says these cells send signals
[02:36.92]to the area of the brain that controls
[02:40.29]what has been called the natural sleep-wake cycle.
[02:44.70]He says there's a lot of blue in white light,
[02:49.13]this explains why the blue light and white light hamsters
[02:54.69]appear to be more depressed
[02:58.03]than the hamsters see red light or darkness.
[03:02.36]Mr Nelson has suggestions
[03:06.31]for people who work late at night,
[03:09.03]or those who like to stay up late.
[03:12.28]"My recommendation is
[03:13.96]if you are just living a typical
[03:16.34]mostly active [life] during the day,
[03:18.30]mostly inactive at night,
[03:19.42]you want to limit exposure to TVs which are quite bluish
[03:23.64]in the light they give off
[03:24.98]and computer screens and things like that.
[03:27.43]You can get filtered glass,
[03:29.09]you can get filters on your computer screen
[03:30.95]and filters on your eReaders
[03:32.16]to put it more in the reddish light."
[03:34.86]The report on the effects of light on emotions
[03:38.72]was published in The Journal of Neuroscience.