She had drifted into a light sleep.

她已经慢慢进入了浅睡眠。

《柯林斯英汉双解大词典》

She drifted into a light sleep.

她迷迷糊糊地睡得不沉。

《牛津词典》

Your body needs to experience all three steps of sleep—light sleep, dream, and deep sleep—to fully repair itself.

你的身体需要经历睡眠的三个步骤——浅睡眠、做梦和深睡眠——从而进行完全的自我修复。

youdao

So much light in the sky would not let his daughter sleep.

VOA: special.2009.03.28

It then waits till you fall asleep then starts the timer, waiting for you to get roughly 26.5 minutes of shuteye, before rousing you during a light sleep cycle.

ENGADGET: Jawbone Up review (2012): a reboot and a shot at redemption

Instead of making a loud noise at a predetermined time, the Smart Alarm gently vibrates when you're in a light sleep, somewhere around the time you'd like to wake up (up to 30 minutes before you've actually set it).

ENGADGET: Jawbone Up review (2012): a reboot and a shot at redemption

Light and quality of sleep are well-known to be linked, as anyone who has ever pulled a night shift will attest.

ENGADGET: Alt-week 12.08.12: The oldest known dinosaur, lighting up a space station and the black marble