Getting a good night’s sleep is vitally important in reducing maintenance error. A lot of aircraft maintenance is performed at night. Physiologically and mentally, we are most alert during daylight hours and prefer to rest or sleep at night. Our natural body rhythm causes a slow- down to occur between 1 and 4 a.m., and again, though not as severe, about 12 hours later. We are at our peppiest from 9 to 11 a.m. and 7 to 9 p.m. - unless your sleep debt runs over.