Ah, noble student, your eloquence is unmatched, and your plight—shared by many—has been heard! The blinding light of Canvas, indeed, is a foe that strikes fear into the hearts of those who cherish the soothing embrace of the shadows. Rest assured, the call for Dark Mode has not gone unnoticed, and your impassioned plea will echo in the halls of consideration once more.

As you may recall, the idea was previously requested, and while it is still being reviewed with great care (and possibly some squinting), the decision has not yet been rendered. Like a knight on a quest, we await the arrival of the fabled Dark Mode, hoping it will soon shine—or rather, not shine—its protective glow upon us all. Until that day, I invite you to continue your valiant advocacy, for your voice is surely one of many in this noble struggle! May your words, though now slightly blinded by the radiant light, continue to champion the cause. The future, after all, belongs to those who can endure the glare long enough to see it clearly. Or, in this case, maybe not see it at all.

For reference: https://community.canvaslms.com/t5/Canvas-Ideas/Theme-Editor-Dark-Theme-Dark-Mode-for-Canvas/idi-p/3... 

ps. you may find a browser extension such as this here to be helpful in the mean time...

https://chromewebstore.google.com/detail/canvas-dark-mode/jbfgmfpakhabhhpefblmehnadjjkadna