Do dogs know to be more vigilant at night?

ALTHOUGH DOGS SEEM LIKE THEY ARE COMPLETELY OBLIVIOUS WHEN THEY ARE SLEEPING, THEY ARE SO ALERT AND AWARE, MORE THAN YOU WILL EVER KNOW...THEY ARE ALOT MORE 'KEEN' WITH THEIR HEARING AT NIGHT, AS IT COMPENSATES FOR THE LACK OF SIGHT/MOST DOGS ARE COLOR-BLIND ANYWAY...BUT, SINCE LIGHT AFFECT EVERYTHING-DAYTIME THEY SEE MORE...SO AT NIGHT THE HEARING IS MORE PRONOUNCED!!!