unpredictably

Because the cave fish may not need less sleep—they may need to stay awake to forage more in an environment where food can be scarce and appear unpredictably.

因为穴居鱼可能并不需要睡得更少——它们可能需要保持清醒，以便更经常地在食物短缺和食物不常出现的环境中觅食。