Deluge
I'm running Deluge 1.3.11 on Windows 8.1 and I was surprised to see it let Windows go into sleep mode as I left it alone for 30 minutes...
I was going to report a bug but I'm detected as "spam", I type the captcha correctly and press Enter but it simply doesn't let me in (tried a dozen times).
So here it is...
It's not expected behavior therefore a bug.