definitely no tv before bed time. in fact may be make it no tv after 6pm. it doesn't matter what she's watching, the TV/computer over excites the brain and she won't get a restful sleep. I don't know if you have ever seen the disclaimer/warnings on some video/computer games and how it may affect some people because of the flashing lights, etc... just keep that in mind. By the way, that 'no tv/video games after 6pm rule it's tough to keep... but worth it...I don't always succeed either)
I saw your comment of 'no caffeine before bed time'... (Please note that I'm not trying to be judgemental) four-year-olds should not be having any caffeine... (well I understand there is a small trace in chocolate) but anything with measureable caffeine should be eliminated from her diet...
While looking at the sugars, first cut out the high fructose corn syrup --it may help a lot with the melt-downs. then work on the other sugar. my son cannot tolerate high fructose corn syrup and it's a pain to avoid it! if he drinks fruitpunch w/ high fructose corn syrup... a few hours (and up to 24 hours later) the slightest thing will set him off.... I mean it doesn't matter what you do, it's wrong. everything it's wrong with the world for about 20 minutes. It took me a long time to figure out what it was (over a year). I used to compare it to the effect alcohol has in some people that all it takes is one drink and then they start telling people what's wrong with them and everything they've done wrong for the past 10 years...it might sound kind of funny until I realized that it's messing with his brain! so HFCS banned from our house.
Personally, I think that all that hype about not using sugar... it's all marketing to get us to use something more profitable for he companies. And like the song says, a little bit of sugar makes the medicine go down. (I never thought I'd be quoting Mary Poppins at 6:30 in the morning!)
I don't know if you want to try and switch singulair to the morning time. Oh, when my daughter was on singulair for about a month, her personality changed and it didn't help her asthma/allergies at all. Good luck! ~C.~