Thanks Robin for your replies......... Power management settings are all verified, but I did find an available update to the BIOS and also 3 driver updates (video, network and chipset).  So I installed all of those items and computer is now current on all software. Used it for a day and the problem is still there, but intermittently which makes it difficult to understand.   If anybody else has any ideas, I'm all ears!   
Hey guys, just set up a Dell Inspiron 15, 2 in 1 with Windows 10, the Intel i5 processor and 256 GB SSD. What a screamer coming from a 6 year old Toshiba with a spinner drive and a dog processor!   This new Dell really is working well and I like it a lot.  But there is still one thing that I haven't been able to figure out. I use the laptop on and off frequently throughout the day, so I put the computer into sleep mode in-between sessions.  MOST of the time, it stays in sleep mode.  But SOME of the time, it just wakes up on its own for no apparent reason.   I use the touchpad to wake up the computer out of sleep mode (to save on the power button over time) but the touchpad has never been touched when it wakes up on its own.  I am using a Microsoft wireless 3500 mouse and I went into settings and under power management, unchecked the box which allows the mouse to wake the computer. What am I missing?  The weird thing is that this is an intermittent problem, not solid.  Sometimes the hardest quirks to track down.  Thanks in advance for the help!  
Intermittently wakes up from sleep?