Most of us will automatically set our clocks ahead one hour in observance of Daylight Saving Time (DST) and besides feeling a little sleepy the next morning, we won’t give it a second thought. However, adjusting your clock on Saturday night or Sunday morning could leave you with a 40-60 minute sleep deficit by Monday morning, and it’s this seemingly insignificant loss of sleep that can cause problems.

Research shows on Monday and Tuesday after the time change, our risk of having a car accident increases by about 6%. Groggy people waking and driving to work in the dark are more prone to accidents. Our chance of being in a workplace accident increases, too, as does the severity of those accidents. In the days following the shift to DST, workplace productivity traditionally plummets as well with a documented increase in “cyber-loafing.”

DST was enacted during World War I to decrease energy use. Benjamin Franklin first advocated for the practice in 1784 because he noticed people using candles at night and sleeping past dawn in the morning. By shifting time by an hour during the summer, they would burn fewer candles and not sleep through the morning sunlight.

However, some observers see nothing but downsides in their data to setting the clocks ahead, even going so far as to dub the Monday after the time change “Sleepy Monday” or “Risky Monday.” Tuesday and Wednesday are more dangerous than usual, as well. However, the risks begin to decrease as the week progresses.

Also, the time change does not save on energy either. By facilitating more outdoor time, it actually prompts us to spend more money at amusement parks and local sporting events, and spending longer evenings out sends us to the ATM and the gas pump more often.

The impacts of DST are likely related to our body’s internal circadian rhythm, our internal “clocks.” The problems with DST are worst in the spring, when we’ve all just lost one hour of sleep. The sun rises later, making it more difficult to wake in the morning. This is because we reset our body clocks using the light. When these clues change abruptly, it causes confusion. To help offset this confusion, try going to bed an hour earlier when you set your clock ahead.