Night leads are more urgent, not less
A homeowner filling out a request at midnight is not browsing. Something is wrong right now, and the emotional temperature of that request is higher than anything that arrives at 2pm on a Tuesday.
That urgency cuts both ways. It means the job is real and often larger. It also means the decision window is shorter — by morning they have booked whoever answered.
The morning reply arrives into a closed decision
Replying at 7am to a lead from 11pm feels responsive. From the customer's side, eight hours passed in which three other businesses answered. You are not late by an hour; you are absent from the entire conversation in which the choice was made.
What can actually be done
An honest holding reply beats silence by a wide margin: acknowledging the problem, saying when a human will call, and asking one useful question keeps you in the conversation without pretending someone is awake.
What does not work is a generic auto-reply that says nothing. It reads as an away message, and an away message tells the customer to keep looking.