Nighthawk is a recurring thought that only seems to strike you late at night -- an overdue task, a nagging guilt, a looming and shapeless future -- that circles high overhead during the day, that pecks at the back of your mind while you try to sleep, that you can successfully ignore for weeks, only to feel its presence hovering outside the window, waiting for you to finish your coffee, passing the time by quietly building a nest.

“夜鹰”指大半夜在你脑中反复出现、让你无法入睡的一些思绪，比如：还没完成的任务、难以摆脱的负罪感、黯淡无光的未来，等等。这些事白天在你头顶盘旋，你在想要入睡的时候突然对你迎头一击。你可以好几个星期对其不予理睬，但它们会一直在你窗外盘旋，等你喝完那杯咖啡，看着你随手搭些小玩意打发时间。

For example:

I have been disturbed by nighthawks of several deadlines lately.

我最近一直被几个要到期的任务困扰，无法入眠。