Well then they should add that to the game. Loose enough sleep and you start fighting enemies that aren't there. Resulting in you waisting ammo on your hallucinations.
Caff-o-Nitro-Maximate!
Ask your doctor if it's right for you!
Do you spend too many hours in the day sleeping? Do you have too much work to do and too little time? Is your boss a megalomaniac who insists that you work 36 hour shifts per day?
Stay awake for longer with Caffonitromaximate! You'll have more energy than you've ever had before. Power through your feeble human trappings... and become Maximated!
'Warning: Use of Caffonitromaximate may cause: Amnesia, Painful Death, Rectal Seepage, the growth of warts, forgetting the birthdays of loved ones, Exploding Tumor Syndrome, Cancer, Bad Breath, Foot Rot, Gill Rot, severe Dry Skin, Allergies to Shellfish, the growth of a shell, Schizophrenia, Mild to Serious bouts of Insanity, Hallucinations, Complete Psychosis, various forms of fungal infection, Gender Instability, Dark Humor, Diarrhea, Constipation, a belief in Fairy-Tale Logic, and in very rare cases, Insomnia. You should not take Caffonitromaximate if you are pregnant or capable of making anyone else pregnant. If you notice any sudden to severe cerebral hemorrhaging, consult your physician immediately. Results may vary.'