Steps or suggestions that can be done to overcome the problem of imbalanced diet ?

Eat smaller meals and snacks more frequently. ...
Talk to your doctor. ...
Avoid non-nutritious beverages such as black coffee and tea.
Try to eat more protein and fat, and less simple sugars.
Walk or participate in light activity to stimulate your appetite.

Because without physical activity, the body has extra "energy" if you will, and so when it is time for bed you are not tired, so you end up staying up all night. also there is probably an effect on your internal clock, which messes with your melatonin production which goes hand in hand with your sleep cycle

True your body needs vitamins such as protein, vitamin d, fish oil etc