I've just moved to Nexus 5 from iPhone in the last week. My iPhone was solid and rarely rebooted itself, maybe once or twice in the 18 months I had it. I've had my Nexus 5 for three days and it has restarted itself maybe 5 or 6 times in the last 2 days. I have the phone encrypted so if I don't notice it restarting, the thing is offline. Not too happy, any way I can diagnose what might be causing it?