Today I managed to function on only two and one-half hours of sleep, though it seemed like much less. The throbbing headache that kept me from sleeping did not dissipate until it was time for my alarm to sound. At that point, I just lay in bed waiting for it to go off so I could turn it off. I managed to sleep through the sunrise, but the dogs' activity ensured that I would not stay in bed much longer than that.
Today, though is not the day I am going to worry about. Tomorrow, a work day, is the day I dread. As I have aged, I find that insomnia's effects are generally delayed by a day, so in this case, it means I'm going to be exhausted on a work day, rather than on the weekend, as I would prefer.
Of course insomnia does not come on a schedule. It happens at the most inconvenient times.
Fortunately, caffeine comes in many convenient ways.