Digital screen time before bed can have a negative impact on the quality of your sleep. A US study found that as little as eight minutes of exposure to blue light keeps you mentally stimulated for over one hour, which tends to throw off the body’s circadian rhythm or biological clock.
Exposure to blue light suppresses the production of melatonin, a hormone that induces sleepiness. Melatonin release in the evening helps you relax before bedtime. Suppression of melatonin can cause you to stay up later and sleep less than you normally would.
Seeing something right before bed that either makes you upset or happy can trigger a response that prolongs falling sleep, which consequently delays REM (rapid eye movement) sleep. These emotions can leave you staring at the ceiling for hours feeling wide awake.
circadian：形容詞，（動植物的）晝夜的，約1日的（節律，週期）。例句：Our circadian clock makes it difficult to sleep during the day.（晝夜生理時鐘讓我們很難在白天睡覺。）
stay up：片語，熬夜、深夜不睡。例句：We stayed up (late) to watch a film.（我們熬夜看了部電影。）