Twice a year we have to switch our clocks, but do our internal clocks adjust to the change? Even though it's just an hour difference, many times we can quickly feel our mood enhance with the more daylight we get, or feel the blues when the days seem darker and shorter. But what causes this swing in mood and who does depression affect when it comes to this seasonal time change?

The early switch to daylight saving time this week has mental health experts concerned that people suffering seasonal affective disorder will have a setback (News, March 8). "Research shows that it's the delay in sunrise -- not the overall hours of sunlight -- that has the biggest effect on mood during winter," says the Los Angeles Times. "People in the north have more depression, but so do people who live on the western edge of each time zone -- where the sun rises later."

So it's predominantly the sunrise, not the sunset that can make you feel less than cheery. And depending on your time zone you could feel the affects of this type of mood disorder more than others. It's not just a myth, the change or delay in daylight can really affect mood!