i was only on 450mg of lithium for 30+ yrs. i'm 74 and when first diagnosed with hypomania in my 30's i'm sure none of the dr./research then indicated the long-term damage lithium does, but it worked for me. i'm not on any mood stabilizer now; briefly tried geodon and lomotril but had bad effects; i'm very in tune w/my body and mind; retired and happily married for 34 yrs. w/little stressors other than covid and yes, a mood stabilizer might improve my sleep but i'm not ready to try another. yes, it takes 3 meds at nite to sleep most times and yes, i have benzo tolerance but i've learned how to live with it and sleep is my biggest issue now. if i don't get those 8 medicated hrs., i'm totally trashed the next day and must sleep to catch up; cannot power thru lost sleep but i have the luxury of staying in bed to catch up. i exercise hard 6x/week; drink only 1 glass of wine per week and have a healthy lifestyle. any anti-depressant tried 30 yrs. ago moved me into mania because depression isn't on my bipolar spectrum. ask your medical person what he/she knows about lithium damage to thyroid/parathyroids (had to have mine removed) and eventual kidney issues after 30 yrs. on 450mg....but it did work for me.