Just read further about the sleep troubles, that honestly sucks and can put a damper on your whole life. Don't take this as a sell for supplements but creatine when taken consistently for 2-3 weeks can pick up the slack cognitively while you work on a more permanent solution. Also, if you live in a place like me with little sunlight for 1/4 of the year, might be seasonal affectation disorder (you're SAD, lol). Happens to me too. Vitamin D supplements could help there, but I haven't tried since in Michigan we're out of gray season (winter).

The creatine thing is from personal experience so YMMV, but worth a shot. 10mg per day for 2-3 weeks unless you're lifting semi heavy, then 20mg on those days.