Cleveland Clinic:

Like a trusty guard dog, your smartphone probably rests right next to you (or even under your pillow) every night when you go to sleep. You’re able to answer calls, texts and emails at a moment’s notice – even during the wee hours of the night.

And isn’t that the best part about technology? Always being connected and never truly shutting down or logging off?

Not so fast. You probably don’t even realize how your smartphone habits are affecting your sleep and your brain’s health. What may seem like a harmless habit to you – jumping into bed and opening up your phone – can actually have a big impact on your overall health.

1. It keeps your mind psychologically engaged

2. The blue light from the screen suppresses melatonin

3. The alerting properties delay sleep

生词短语：

guard dog

守卫犬

wee

很小的; 极小的

psychologically

心理上地；心理学地

melatonin

褪黑素; 褪黑激素