Tonight, daylight saving time starts. At 2 o'clock, our clocks move forward to 3 o'clock, so we lose an hour of sleep.
Why do we use daylight saving time? Mostly to save energy. By moving the clock forward, we use more daylight in the evening and use less energy.
Whether we really need daylight saving time is still argued. Some say it saves energy, gets people outside more, and fits better with daylight hours. Others say the energy savings are small, it messes up sleep, and it might not be as useful in modern life. It depends on what people think is important.