This is a repost from tudiabetes... Just curious of your experiences with this:

have been having some issue with my sensor while I am asleep. Most of the time it goes out of range, or I get the 3 sets of ??? . the dexcom is usually right next to the sensor. Anyone have this issue ever?

I do sometimes.  It seems like some sensor batches are more prone to this than others.  Of course you never know till you put the sensor on and it does this, yeesh!  One thing that has helped me is to keep the receiver on my pillow rather than my nightstand.  Having it closer to the sensor seems to help.  I also notice that where the sensor is on my body seems to correlate with more ??? readings.  I get them more when the sensor is on my leg or upper butt versus my stomach.  Don't know how helpful this is but I wanted to share...

Someone else told me to try it in my bed with me, and I had a full night of success!  I am also going to try a different spot next time, I've been using the upper part of my leg (more towards the butt).  Hopefully this all helps!

I sleep with mine.  If I put it on the bed stand sometimes I don't get reading.  I haven't missed readings in awhile but I was having the same problem before

2 nights in a row with readings.. I guess in the bed works!