The heavier foods we eat the harder it is for us to function. It makes our body divert energy to the immune system and the digestive system, therefore we lose vital energy that can be transmuted into happiness.
Not to say that all of our organs are interconnected to our mental and emotional states ( representing different chakras ).
Regarding sleep the more energy we waste the more sleepy we get and the more high energy food we intake like energy bars and drinks can lead us to insomnia :)
Cheers !