Sleep Wake Failure

I have a relatively new 27" 5K iMac. (The 3.4). On two separate occasions (to my knowledge) the iMac has restarted itself while it was asleep and I was some distance from it - on the couch. Hence, I wasn't performing any action such as touching the track pad or keyboard to wake it.

Following restart each time and then logging in, the attached error has resulted. I've reached out to Apple Support via phone, but the advisor didn't seem to know much.

Following each time after restart, the OS states I need to key in my password in order for Apple Watch to unlock it. We know that wearing the Apple Watch can be used to unlock/wake the iMac, but I'm not sure this is related or it can be trying to wake it when I'm just sitting on the couch.

Any feedback is greatly appreciated. Thank you.

Screen shot and text of error is below.

No samples for specified time interval

================================================================

status: 0x40003

Code: 0x201000014

Stackshot reason: Watchdog

Graphics: Radeon Pro 570, Radeon Pro 570, PCIe

Memory Module: BANK 0/DIMM0, 4 GB, DDR4, 2400 MHz, 0x80AD, 0x484D413835315336414652364E2D554820202020

Memory Module: BANK 1/DIMM0, 4 GB, DDR4, 2400 MHz, 0x80AD, 0x484D413835315336414652364E2D554820202020

AirPort: spairport_wireless_card_type_airport_extreme (0x14E4, 0x16F), Broadcom BCM43xx 1.0 (7.77.37.31.1a9)

Bluetooth: Version 6.0.7f10, 3 services, 27 devices, 1 incoming serial ports

Network Service: Wi-Fi, AirPort, en1

USB Device: USB 3.0 Bus

USB Device: Bluetooth USB Host Controller

USB Device: FaceTime HD Camera (Built-in)

USB Device: G-DRIVE USB-C

Thunderbolt Bus: iMac, Apple Inc., 33.1