Conan Doyle famously concluded his poem "To An Undiscerning Critic" with the words, "The doll and its maker are never identical" to point out that he was not Sherlock Holmes. That, of course, does not rule out Conan Doyle basing parts and pieces of Sherlock Holmes's life on his own experience. Take this passage for example:
"Even the triumphant issue of his labors could not save him from reaction after so terrible an exertion, and at a time when Europe was ringing with his name and when his room was literally ankle-deep with congratulatory telegrams I found him a prey to the blackest depression."
Such words do not come out of the void by magic. And while Conan Doyle definitely had other people in his life who fell prey to depression, he was also a man of accomplishment, a man who could decide upon a goal and work hard to achieve it. And we know he succeeded in many a goal, even by the summer of 1893 when "Reigate Squires" was published, containing the above passage.
If you've ever worked hard to put on an event, you know that the greatest congratulations always fall on you at that moment your work is done and you are the most exhausted -- the moment the event is done. Other massive projects might not get the praise quite so immediately, but the cycle can still hold. And even when the effort made is just one to enjoy one's self as much as possible, like at a Sherlock Holmes weekend, when it's over, and everyone else would expect you to be most pleased . . . well, you're tired and vulnerable. Vulnerable to flu bugs, depression . . . even just disappointment at returning to the routines you had before you got to go to war with Professor Moriarty and throw the rules out the window for a while.
Am I equating Sherlock Holmes's foiling of Baron Maupertuis and his colossal Netherland-Sumatra Company schemes to a Sherlockian just going to Atlanta or Minneapolis or New York for the weekend or one of our own little projects? Well, yes . . . he wasn't real, you know (something I can safely say, having referred to Conan Doyle at the outset). But Sherlock Holmes's trials and tribulations are like the man himself -- a heightened version of the rest of us. And his post-event drops are likewise enlarged. Watson doesn't have to travel a very long way to pick us up.
We get to wonder what particular incident in his own life might have inspired Conan Doyle to pen those words about Holmes in that room full of telegrams. A loss of vigor after a round of congratulations for one of his achievements? Just another thing that connects Conan Doyle and Sherlock Holmes and the rest of humanity, which is a big part of why these stories work so well.