Researchers at Loyola University Health System said on average, people sleep about 40 minutes less than normal after the switch.
Other research shows there's a higher risk of traffic accidents and workplace injuries the Monday after the change.
A previous Swedish study found the number of serious heart attacks jumps 6 to 10 percent on the first three workdays after the start of Daylight Saving Time.
To help reset your internal body clock, expose yourself to sunlight in the morning as early as you can.
