When I am using briquettes, once I get stable temps for a couple of hours, I go to sleep, and sleep like a baby! I've had a few surprises when I woke up, but never anything disastrous. Briquettes always seem to cool as the night goes on. My theory on this is that once all the coals are alight, the ash coating thickens on the lit coals and the the coals burn cooler as O2 must find its way through the ash coating to support the combustion.
However, lump doesn't undergo this process. The ash coating on lump charcoal is much thinner than on briquettes. Oh, and I do use a remote thermometer with high and low alarms. It does sometimes go off when I am using only lump.
Cheers