Facebook Last ActiveWatch
It's not always accurate anyway. When my boyfriend's on Messenger or Facebook, if he just locks his phone without closing the app (which he does ALL the time), it flicks him onto "active" every time he gets a notification. I asked him about it because it looked like he was opening his phone to read my message, then seeing the first bit and just turning it off again - which isn't unreasonable, but sometimes the messages were important. So we experimented with it a bit, and that's what it was. Weird.
Also, if they're in bed or busy, their phone is likely on silent anyway - so send your message and they can read it when they're ready .
I was awake in the middle of the night and it was showing that my friend was online, so I rung him....he wasn’t online, was actually fast asleep and I woke him up :/