alt Hacker NewsApple's definition of "sleep" is unique, to put it mildly. My MBP may be "sleeping" but it will still aggressively connect to any wireless interface. Sometimes when passing by with my Bluetooth headphones, the MBP will often steal my current connection.
When a device goes to sleep, I don't expect it to interact with anything, even if I didn't deliberately turn off all wireless communication.
Apple is the only one doing this. I've had dozens of linux and windows devices by now, and Apple are the only ones to aggressively maintain or connect to wireless while sleeping.
Apple is not the only one doing this. Windows, depending on how its configured and the hardware in it, will keep WiFi and even Bluetooth devices connected even while "asleep".
Example: I go out to the park with my Windows laptop. I turn on the computer. I pair my headphones and hop on my phone's wifi tethering. I do some stuff. I close my laptop lid, the system goes to "sleep". My headphones still think they're connected. My phone still shows the laptop is a client. I walk around the park for an hour. My headphones are still connected, my laptop is still a client on the tethering. I sit down, I open my laptop, it wakes up, and it's still connected to everything.