Yes. I use an RM script to reboot my hub on a weekly basis, (this was an old method of keeping a C4 happy). On a couple of occasions I entered my house about 10 minutes after a reboot and nothing happened. Then as soon as the hub went to "normal", the siren and intrusion alerts went off.
I understand the hub not functioning for a few minutes, perhaps 5 maximum, on a reboot and that time will vary based on the number of apps and devices.