Yes, I agree with Patti (Birdwoman), he is waaay too heavy. The thing with birds is that they are better off been a bit skinny than they are overweight -even if it's just a bit- and, if he really is over a kilo, he is VERY overweight (their average weight is between 450 and 800 grams). If I were you, I would re-evaluate his diet because I feed my birds as much as they want to eat and none of them are overweight -when it comes to birds, it's not only quantity, it's also what you feed them because, for example, pellets, been so dry and concentrated, can make them fat if you free-feed them.
If he is no longer screaming all the time, you are doing good!
One word of caution though, you can't leave the light on at night and I'll tell you why. Mammals only have photoreceptors (cells that perceive light) in the eyes so, when they close them, no more 'reaction' to whatever light there might be, but birds have them in the eyes and inside their brain (their cranial bones are so thin, they allow light to shine through them into the brain) so the photoreceptors there can be activated by it even when they are fast asleep. This is because birds endocrine system is governed by light (to birds, light is more than something that allows them to see, it's an actual nutrient and glandular activity trigger) and long exposure to it means breeding season so, even if you put him 'to bed', if you are leaving a light on at night, his body is registering light all night long. There are myriad studies done with birds and their exposure to light at night and all of them tell us that this will, indeed, screw up their endocrine system - and this can mean an overly hormonal bird (which is pretty easy to get with cockatoos because they are 'hormonal' birds) which translates into aggression (usually, toward anybody who is not their chosen one).