Change in night time behavior

I am starting to worry about my cat. I have had him for about 5. During the day he is perfectly fine. He is playful and loving. But at night, he has been hissing at me and full on scratching me out of the blue. And has been just vishous and mean. But it only happens at night. Do u have any suggestion or tips?

Is it possible there are visiting tomcats outside that are upsetting him?  You said you have had him for about 5 --but 5 what?  5 days, 5 months, 5 years?  It is not unusual for male cats to be prowling at night, and even if you don't know they are there, he will know. It is mating season right now in the northern hemisphere and the boys are out looking for love.  This does not go over well with inside boys.  Start checking outside at night, notice if there are cats, or if you could install a motion sensitive light, you would quickly know if the light goes on that something is moving out there.  If this is the case, you need to set up deterrants around your house to keep other cats away.  There are motion sensitive sprinklers, noisemakers, etc. Also, if your boy is not yet neutered, getting him neutered as soon as possible should also be helpful in reducing his aggressive behavior.