What is there to depression evaluation other than a phq 9? Because I can tell you that when I'm tired and stressed, the number is high. And when I'm not, it's not.
You hit the nail on the head that the PHQ-9 winds up being more a measure general stress/distress than depression. I do not like the PHQ-9 in assessment, although it can be useful in monitoring symptom severity over time.
There is a lot to evaluating for depression, but it can be good to think about whether one or both of the core symptoms are present: depressed mood and/or diminished ability to feel pleasure (latter can manifest as diminished interest). Low energy is a manifestation of a depressive disorder if it is a product of one of those symptoms, rather than just because one isn't sleeping well. A good way to discriminate would be how someone feels after they have been allowed to sleep as much as they need without interruption and wake up naturally. If afterwards they have their normal "get up and go"-ness, then that would be a pretty reliable sign that the issue is inadequate sleep rather than mood.
An important question when considering mitigating the effects of sleep deprivation with stimulants is if it is being used in a short period of impaired sleep to bridge to period of adequate sleep (e.g. person doesn't sleep enough during the week but catches up on the weekend) or if it is going to be used chronically and persistently (e.g. "I will sleep when my children are in college and/or I quit EM"). The former can be reasonable, the latter is setting oneself up for problems (e.g. health complications, escalating doses, dependence). A good way to think about it would be 'does this sound reasonable if I replace the word "sleep" with "eat"?'
Bupropion is a mild stimulant that is not a controlled substance, and absent seizure or arrythmia diathesis is pretty safe to try; it also probably won't raise eyebrows if you self-prescribe or ask your physician for it, unlike other stimulants.
Modafinil/armodafinil are in theory more specific to promoting wakefulness, but are controlled - adrafinil is not federally regulated last I checked, but some states have caught on to its existence and started regulating it. Methylphenidate and amphetamine-type stimulants are more powerful but obviously more regulated.
Cocaine obviously has strong "get up and go" inducing effect, but besides the legal issues with it, the half-life is too short to keep you going throughout the day - however, if you imbibe alcohol before using cocaine, then it will be metabolized into the cocaethylene active metabolite pathway and will last much, much longer. Clinical pearl: Be aware that the effective duration of action of cocaine is dramatically prolonged when the patient has been using alcohol (I recall a recent patient that spent the better part of 2 days intoxicated with cocaine in the ED), and the ethylated metabolites of cocaine are typically not checked for on UDS.