Left to itself, our brain likes to remind us of important tasks only when it has flushed the cache of all menial labour.
All too commonly do we see people spend all their day taking care of aimless busywork (which their brain can easily process), and then just as their head hits the pillow, they remember something important that must be done.
All too often, people ignore this sudden realisation, choosing instead to push it off until "tomorrow". They do not respect the brain's massive nighttime workload, and try to shove another (trivial) task at it for safekeeping. Needless to say, the brain doesn't remember such tasks very well, and the next day, the cycle repeats itself.
Do take this seriously; people have killed themselves with such negligence. (don't forget to take your meds)