This year, daylight savings time starts at 2 a.m. on Sunday, March 9th. When you turn your clocks ahead an hour, remember to replace the batteries in your smoke and carbon monoxide detectors. Also, take a minute to check the age of your alarms. The Massachusetts Department of Fire Services wants to remind you that carbon monoxide (CO) alarms need to be replaced every 5-7 years and smoke alarms every 10.