A Splendid little insight

I admit, we worked really hard last week. We painted until my arms ached from reaching overhead. We carried furniture in the heat. We put together bookshelves, desks and tables involving 1,000s of screws until my hands were bruised and achy.
Then, I had the weekend off and I admit that I partied a bit, sacrificing some sleep to get the most out of spontaneous happenings in or near water.
Finally, I got up Monday morning tired, went to work tired, drank coffee and was tired, had a massage and was tired, put together my new bookcases for the house - tried, and fell asleep.
I overslept by three hours on Tuesday morning.
I took a nap Tuesday afternoon for two hours. I went to bed at 9:30 p.m . Tuesday night.
I woke up and worked from 3-5 a.m. Wednesday morning, again slept until 8:30 and woke up with a headache.
I got to work and made myself coffee. The headache got worse.
Now, in an attempt to save calories I had purchased and was using Splenda to sweeten said coffee.
And that's when the headache started to feel like a migrane and I finally put two and two together. I am allergic to all other artificial sweetners, why not Splenda? Well. No reason. It was the cause of the aches, the fatigue and the horrible headache.
I took a Migraine pill and drank some black coffee and 64 oz. of water. The headache receeded and the day was saved.
How, exactly, can I be so dumb? If you know the answer to this, please write it on the back of a $100 bill and send it to me right away.