Strange wake behaviour on AC power

[nipponham]

I’m noticing something strange. I finished using my SP3 and pressed the power button to put it to sleep. I’m working on other things at my desk for a few minutes and suddenly notice the screen turn on. Nothing on the SP3 was touched nor a mouse used. I just shook my head and pressed the power button again to make it sleep, but this time the screen came back on after a few seconds. I put it to sleep one more time but it again woke up after a few minutes. I left it as is to see what it would do and it went back to sleep by itself after about 45 seconds. I continue working on other things while keeping an eye on the screen. After 5 minutes of blissful sleep I convince myself that it was a one-off anomaly and stop worrying about it. However, sure enough, after a few more minutes had passed, the screen turned on again by itself and went back to sleep by itself after the same 45 seconds or so.

So what’s going on here? My understanding is that only user-initiated actions (such as moving the mouse or tapping a button) can turn the screen on from a connected standby state, is this not correct? I don’t know if this makes a difference but it’s on AC power. Haven’t tested for this behaviour on battery.

I’ve been watching the device now for about 10 minutes since its last wake-up but it’s still sleeping, for now.

 

[young blade]

You should try to see if it still happens when you disconnect all USB devices.

 

[nipponham]

No USB devices attached.

 

[young blade]

I also experienced this strange behaviour when I had my SP2 (Only once).. Now I'm waiting for my SP3 to arive..

 

[jnjroach]

Run the Sleep Study and see what is activating the device, or you have a TSR that is fighting with Connected Standby.

 

[nipponham]

Thanks jnjroach. I ran sleep study last night and saw windowscommunicationapps being activated a number of times during the period I experienced this behaviour and this in turn was activating network activity. It makes sense as apps must have been doing some background activity. What doesn't make sense is the screen turning on by itself. Although it was only awake for under a minute, I can see repeated occurrences to be a cause of unexpected battery drain during what is supposed to be sleep/connected standby.

I haven't had a chance to monitor this behaviour since the last occurrence yesterday (nor am I interested in watching a blank screen) but I'm going to keep this in mind and see if I notice any other related behaviour.

 

[jnjroach]

That is Skype or Lync typically....​

 

[nipponham]

I don't have Lync but I do have Skype. But I wasn't using it yesterday, nor do I have it set to work in the background, because I have my smartphone to do that. I only turn it on for video conferencing.