The question of whether red-eye flights are worth it usually gets answered by the price, and the price is the one number that hides what actually matters. An overnight flight is often cheaper, and sometimes it saves you a hotel night on top of that. Other times it hands you a bargain fare and quietly takes a full working day in exchange. Same seat, same route, completely different trade.
The fare tells you what the ticket costs. It says nothing about the day on either end.
The day you lose, and the one you save
A red-eye can go one of two ways. The good version: you board late, sleep through most of the flight, land in the morning, and walk into your trip with a hotel night you never had to pay for. You swapped a night in a bed you'd have rented anyway for a night in a seat, and you came out ahead.
The bad version looks identical on the booking page and feels nothing like it. You don't really sleep on planes. You land at 6am wrecked, reach a hotel that won't have your room ready until three, and spend the first day too fried to do anything with it. Or you take the return red-eye, land at dawn, and lose the next day to recovery instead of work. That's a day gone, and the fare never charged you for it on paper.
Are red-eye flights worth it? Count the lost day
This is the same math we do with what a layover is actually worth: put a rough dollar value on your time and set it next to the savings. If the overnight fare is $120 cheaper and it genuinely replaces a hotel night, that's an easy yes. If it's $40 cheaper and it costs you a day you'd otherwise spend working or actually being on vacation, you just paid to be tired.
Be honest with yourself about whether you sleep on planes. Some people do, and for them a red-eye is close to free time. If you're one of the people who doesn't, the overnight fare isn't as cheap as it looks, in the same way the sticker price quietly leaves out the bag fee.
What we do about it
We won't call a red-eye a deal just because the number is low. When an overnight fare shows up in the three flights we send each morning, it sits next to the daytime options at their real prices, so you can see what the late departure saves and decide whether the hours it costs are worth the dollars. The cheapest departure time and the best one aren't always the same, and only you know which day you can afford to lose.