I've not been to sea in awhile but I used to get it . . especially if there was a bit of motion.
First symptoms of seasickness? Drowsiness.
Add to that dark of night, steering a course cross the English Channel, pitch black, a bit bumpy, ships everywhere, autopilot on. Hard time concentrating, keeping the eyeballs front and center.
Then the skipper (Roy) comes up. Owner, in the aft cabin, says water is coming in. Roy opens the lazarette, jumps in with a flashlight, and says, "OK, Mac, dog her down tight. Let's see where this water is coming from!"
Roy was a bit different . . . two Whitbread races on Royal Navy yachts and a pioneer of the "Why don't we jump into the sea out of helicopters?" group (He later had both ankles rebuilt in the Naval hospital).
Needless to say, I didn't let myself nod off while he was locked in the lazarette.
I thought to myself, "What kind of wimp am I?"
First night out can kill you.