Skip to main content

Verified by Psychology Today


Sunlight: The Natural Appetite Suppressant

Yet another reason why we love our summers

About 30 years ago, a depression associated with the dark seasons of the year was identified. It was called Seasonal Affective Disorder ("SAD")1. For reasons still not well understood, late sunrises and early sunsets caused people to sleep excessively, experience fatigue and disinterest in work and social life and, alas, eat too much. Long hours of daylight starting in the late spring and lasting through most of the summer were seen to have the opposite effect. Formerly depressed, lethargic, often-chubby SAD sufferers turned into energetic, upbeat, salad eaters and many managed to shed their winter pounds along with their sweaters.

For most of us, this transition from a darkness-induced depression and overeating to a gym- seeking, snack-rejecting mild mania is very subtle, like the tiny increments in minutes of sunlight all through the spring. But this past month, my travel schedule made me a research subject for what happens to mood and weight when going from darkness to light.

Almost two weeks spent in Australia, as the country entered the short daylight hours of winter, caused me to be suddenly aware of a creeping fatigue (not related to substantial jet lag). Grumpy mornings waking up in darkness had me seeking out caffeine and carbohydrates in the late afternoon when the sun set hours earlier than the States. Weight gain was checked only because, like any tourist, I spent many hours walking, and the jet lag took away my appetite during the early days of my visit. Who can eat dinner when one’s body says it is 3 A.M.? Moreover, where was I going to find dinner when I became hungry 3 A.M. Australian time?

A few weeks at home, and then a trip to Israel with its endless summer blue skies and brilliant sun flipped my mood, energy and appetite. My traveling companions and I were like Energizer bunnies: charged up and moving constantly. The early sunrises and long sunsets elongated the hours during which we could sightsee. The mounds of locally grown fruits and vegetables available in the gigantic souk (market) made salads a constant feature in the menus we prepared in our rented apartment. My caffeine and carbohydrate consumption all but disappeared in the afternoon. And, to my astonishment, I found when returning home that I had, without trying, lost a few pounds.

Unfortunately, the culture of weight-loss programs do not acknowledge the dramatic effect spring and summer daylight has on losing weight2. Magazines, newspaper articles, and advertisements for diets cluster in the early weeks of January. How many New Year’s resolutions include dropping 20 pounds before springtime? Insisting that weight-loss efforts begin in the depths of winter darkness is usually as effective as forcing one’s jet-lagged body into going to the gym, or eating dinner when it desperately wants to sleep. A friend of mine who had visited China told me that her head narrowly missed hitting the salad plate when she fell asleep at a restaurant a few days after returning home.

June, July and August are the best times to lose weight in the Northern Hemisphere, and as June is already gone, there are only about two months left. The long hours of sunlight (alas, diminishing as we move toward autumn), are a natural appetite suppressant. Long hours of sunlight elevate our moods so that we feel optimistic about taking care of our bodies. Long hours of sunlight also elevate us off the couch, into long walks or finally trying a class at the gym. Extended hours of sun make local produce available at farmer’s markets or your backyard garden so it is possible to feast on newly picked tomatoes, summer squash, or the impossibly sweet tiny kernels of newly harvested corn.

What better combination can be found for removing those pounds added in the winter?

So unless you are planning a trip to the southern hemisphere next winter (when it will be their summer) the time to start that diet is now. And love yourself for doing this.

1) Rosenthal, N.E., Sack, D.A., Gillin, J.C., Lewy, A.J.,Goodwin, F.K., Davenport, Y., Mueller, P.S., Newsome,

D.A. and Wehr, T.A “Seasonal affective disorder: a description of the syndrome and preliminary findings with light therapy.” Archives of General Psychiatry.41 (1984): 72-80


More from Judith J. Wurtman Ph.D.
More from Psychology Today