What can our ancestors teach us about sleep?
We've all heard advice about good sleep hygiene. No phones or caffeine before bed, and make sure that we get a good eight hours' rest. But is this the best sleep pattern, or have we just been led to it by modern life?
Artificial light in our houses and streets means that we no longer have to go to bed at sundown. Having a job to go to at a set time in the morning can be the main determining factor on when we decide to rouse ourselves.
In past centuries, the time of sunset and sunrise had a much bigger impact on people's days. Historical studies have shown that in many parts of the world it was common for people to sleep in two sections, from dusk until around 11 and then from one in the morning until sunrise. This segmented or biphasal sleep pattern is referred to as far back in history as ancient Greece.
So, if modern sleep patterns are in some part due to modern lifestyles and technologies, could segmented sleep patterns be more natural? Some studies suggest that they are. The circadian rhythms that determine when we start to feel drowsy are greatly affected by light.
Study participants subjected to 14 hours of complete darkness a day started to develop a biphasal sleeping pattern. As recently as 2017, similar patterns have also been seen in some communities in rural Madagascar that do not have access to electric light.
They may be more natural, but are these sleeping patterns healthier? Experts caution that the small number of studies carried out means that the risks and benefits of segmented sleeping are not well understood. Nevertheless, some people have found it to be a useful way to find time to be creative.
Psychologist Gregg Jacobs suggests that the period of time that people used to spend awake in past centuries could have been used to regulate stress. Other experts remind us that many people find that they wake in the night, and then get anxious at not being able to get back to sleep, which in itself exacerbates any sleeplessness. Making use of the awake time to do something restful could help people improve their sleep.
If you do want to try it, sleep researcher Mary Carskadon reminds us that we should stay away from bright lights to avoid disturbing our circadian rhythms. You also might want to check that it won't disturb your work and social life too much.
词汇表
sleep hygiene [ˈhaɪdʒiːn] 睡眠卫生，睡眠健康（指有助于良好睡眠的习惯与环境）
caffeine [ˈkæfiːn] n. 咖啡因
sundown [ˈsʌndaʊn] n. 日落，黄昏
at a set time 在固定时间，按时
determining factor [dɪˈtɜːmɪnɪŋ] 决定性因素
rouse [raʊz] vt. 唤醒，叫醒，使醒来
segmented sleep pattern [ˈseɡmentɪd] 分段睡眠模式（黄昏睡到大约晚上11点，然后从凌晨1点睡到日出）
biphasal sleep pattern [ˌbaɪˈfeɪzl] 双相睡眠模式，双段睡眠模式
circadian rhythm [sɜːˈkeɪdiən ˈrɪðəm] 昼夜节律（人体受光照等自然环境影响的24小时生理周期）
drowsy [ˈdraʊzi] adj. 困倦的，昏昏欲睡的
be subjected to [səbˈdʒektɪd] 遭受，经历，被置于…之下
rural Madagascar [ˈrʊərəl ˌmædəˈɡæskə(r)] 马达加斯加农村地区
caution [ˈkɔːʃn] vt. 警告，告诫，提醒
exacerbate [ɪɡˈzæsəbeɪt] vt. 加剧，恶化，加重
sleeplessness [ˈsliːpləsnəs] n. 失眠，缺乏睡眠
restful [ˈrestfl] adj. 令人放松的，有助于休息的
📖 翻译、pdf见公众号【琐简英语】，回复"1"可进【打卡交流群】