In simple terms, DHCP determines if your IP is static or dynamic and the length of time an IP address is assigned. Dynamic Host Configuration Protocol is controlled by a DHCP server. Your router can be a DHCP server...and if you're on a home network, it most likely serves this purpose.
Researchers report that the average adolescent needs eight and a half to nine and a half hours of sleep each night. But in a poll taken in 2006 by the National Sleep Foundation, less than 20 percent reported getting that much rest on school nights.
Adults average about 7-8 hours of sleep per day. Recent evidence shows an intriguing association between short self-reported sleep duration (6 hours or less) and increased risk for coronary heart disease and diabetes mellitus.