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Quick Dose: Why Do Shorter Days Affect Me?

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It’s not all in your head: Shorter days can have a negative impact on your well-being. Your eyes take in the duration, brightness and even the wavelength of light. The effect on sleep is strongly affected by the  blue and green wavelengths, which are more frequent in the summer and in the morning. When the days become shorter, the amount of light we take in decreases, which can disrupts your circadian rhythm.

Whether it’s due to changing of seasons or jet lag, when your circadian rhythm is off, you may experience fatigue, hunger, mood swings, decreased alertness and difficulty sleeping. It’s one of the reasons Daylight Saving time can be so hard on you: Your brain and body needs time to adjust.

For some, the decrease in serotonin and increase in melatonin could play a role in seasonal affective disorder (SAD), a seasonal depression that affects 5 percent of Americans. 

Learn four surprising ways shorter days affect your brain – and what you can do to change it. 

-Phyllis Zee, MD, PhD, Northwestern Medicine neurologist, and Northwestern University Feinberg School of Medicine professor and chief of sleep medicine in neurology, contributed to this article.