Often causes slow movements and loss of sense of balance.

Depressants often cause slow movements and loss of sense of balance. These chemical substances reduce the speed and ability of neurotransmitters to communicate. Included in this category of substances are opioids, alcohol and marijuana related products. Pharmacological-related substances are sleeping pills and pain relievers, to help aid sleep and relax muscles. 

The salt in the sea water dehydrated the sailor because her body could not take in the amount to salt in the sea water

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.