Ah, the promise of e-mail! The minute I started giving out my address to my patients, I fantasized about how much time I would save on routine phone calls and how clear and unambiguous the communication would be.

Indeed, there was a honeymoon period. Could I change a Monday appointment for Wednesday? Of course. Would I phone in a renewal of Prozac? With pleasure. This was really neat: no more phone tag with patients, just simple requests with simple solutions.

Not for long.

“Dear Dr. Friedman,” one patient e-mailed at 3 a.m. “I am having dark thoughts and wonder if I should increase my antidepressant. Can you let me know what you think?”

It was 8:30 that morning when I opened my e-mail and read her message with alarm. What exactly were “dark thoughts”? I wasn’t sure, but I had to assume the worst — suicidal feelings or thoughts — and called her immediately.