Your cat sounds like a smart one! The comments made by authrjenn are valid. He may need a kitty companion. It does not matter which sex the companion is, though. You may not be able to stop him from opening cabinets. Place child locks on all cabinets. Keep the doors to the bathroom closed. Change his diet to all meat, no grain canned food. The higher the protein contact the better. Cats are obligate carnivores and require very high amounts of protein and an Atkins type diet is really best for this. No dry food! Twice daily feedings should be enough for him. Begin with a can in the morning and a can in the afternoon or evening. Mix a bit of extra water into the canned food. The extra water may help to fill his stomach. A 1/2 tsp. of plain psyllium can also be added to the canned food and will help to fill his stomach.
Melatonin can be given at night to try to help get him to sleep at night. Begin with a dose of 0.5 mg. The dose can be increased to 1.0 mg if the 0.5 is not effective. See if you can find a sustained or extended release melatonin product so that it will last the entire night. You may have to go online for this since it is such a low dose.
Is the cat neutered? I have 3 cats and they are 13 now. One cat eats all the time and acts the same way. First of all buy the cat science diet (diet food) and give him/her a small can of wet food 2x a day. (Diet food). Cats are meat eaters until man said they should eat dry food and become domesticated. So by nature they are clan members. your part of the clan. when you lock the cat out he misses you. Cats are also nocturnal. They play all night and sleep all day. They are hunters and you can not hunt during the day.(at least not in a cats world). If your cat is fixed great he/she will mellow out by age 5. If not, that is a big problem. I would guess the cat is fixed, that's why he eats all the time. I would get that cat a playmate. Opposite sex of course, fixed and a few years older. That will solve the company problem and mellow your cat out.My cats are up day and night, but they never bother me before I get up at 4;00 am to potty. I give them one can of wet food split 3 ways.(3 cats). they have feeders down and self feed 24/7 and don't overeat. they know the food is there so they never panic looking into a empty dish. Diet dry will keep the cats weight down. it is very dangerous for a cat to lose weight quickly. It can kill your cat. So slow is the key word here. But after 50 years of raising cats, I can tell you this cat is lonely, needs companionship and a diet cat food. I bet he'll change once he /she gets a buddy.
brooke