For Klingons, the new day starts at dawn, not midnight. So any particular night belongs to the day before it. To a Klingon, wa'Hu' ram would always mean the night leading into the most recent dawn. And DaHjaj ram would always mean the night leading into the next dawn.
I suppose if it was almost dawn and you still hadn't slept it would be appropriate to say this sentence and, in that context, translate it as, "I couldn't sleep tonight."
Understood (??? jIyaj)
jIyaj is good for "I understand".
For "understood", perfective jIyajpu' might also work well, indicating a completed action: your understanding has come to a conclusion.
Most Klingons don't say "thanks" or "you're welcome" or "please" :)
Terrans learning Klingon do sometimes say qatlho' "I thank you", though.