Throughout the summer, local residents need to use quilts when they sleep at night. Electric fans and air-conditioners are not their daily necessities.
整个夏天，当地居民夜间睡眠都需盖上棉被，更难企及电扇和空调作为他们日常生活的必需品。
2
By nine it is dark and, as there is no electric lighting, there is little to do but sleep.
到了九点天已经黑了，由于没有电灯，除了睡觉没有别的事情可做。
3
Humans didn't evolve with electric lighting, so you can't just trust your body for when the best time to sleep is.