Farewell to Sleeping Twice a Day - For Now

Some time ago, I wrote about my experiences in changing my sleeping pattern to consist of two sleeping periods per day - a brief, 60-90 minute sleep in the afternoon or evening, followed by a shorter than usual night's sleep.
I found then that after a period of adjusting to the new schedule, during which I was haunted by strange dreams and a sense of jetlag, I felt much more well rested, and could retain my focus much longer - in particular, I found it much easier to wake up early, and the evenings were a buzz of productivity.
Fast forward a couple of years, and I have finally given up on the notion of sleeping twice a day, and I have returned to the "normal" pattern of sleeping a full night, being drowsy in the mornings and afternoon.
But if it worked so well for me, why did I give it up?