I find that being worried sick about the perpetual delays to our flat-buying project, while prices zoom up to way beyond our abillity to afford another one if this one collapses to be a highly effective way of not being able to sleep. :sob:
One of the exercises we did at the Royal Military College in Australia many moons ago was called Shaggy Ridge. Had two hours sleep per night, and six spoon fulls of food per day for four days. I can pretty much stay awake now for anything.