So, I finally found out why my laptop with El Capitan kept crashing. It took me a while to notice consistent references to
com.symantec.kext.internetSecurity(5.4f4) in the crash report, for which I found a few other online OPs, if you will, in a similar predicament. Although I had already uninstalled my Comcast provided Norton Internet Security, I had to run a separate program to have Norton thoroughly search my computer for any remaining files. A forum post led me to suspect that the offending reference was a kernel extension in
/System/Library/Extensions. The RemoveSymantecMacFiles utility indeed cleared out its files from there. Ever since, my computer has been going to sleep normally and has not randomly crashed for the past few days, as opposed to crashing about every hour.