System76 gazelle does not wake up after hibernation

[sds]

I enabled hibernation as described in
https://help.ubuntu.com/stable/ubuntu-help/power-hibernate.html
and when I invoke hibernation, it seems to work.
however, when I try to wake up, the screen remains blank and the keyboard does not respond
(even though the power light is on)

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: pm-utils 1.4.1-15
ProcVersionSignature: Ubuntu 4.2.0-19.23-generic 4.2.6
Uname: Linux 4.2.0-19-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Nov 29 15:05:13 2015
PackageArchitecture: all
SourcePackage: pm-utils
UpgradeStatus: Upgraded to wily on 2015-10-25 (35 days ago)