Can the timing of your meals affect development of cancer?

Mealtime and Cancer

Mealtime and Cancer

It is now widely accepted that what you eat may help your body resist the development of cancer. For example, proponents claim that eating a diet rich in antioxidants may help strengthen your body’s immune system. But can the timing of your meals have a similar impact? According to a rather complex study by French researchers, reported in the journal, Cancer Research, it may indeed.

The French scientists studied the growth of pancreatic tumors in mice. The control or unregulated group of mice was given access to food on an unrestricted schedule; the experimental mice, or meal timed, group was given access to food only at specific intervals during daylight periods. Researchers reported that the tumors grew almost twice as fast in the control mice as compared to those in the meal timed group. Based on DNA micro-array analysis and other data, the investigators also concluded that the suppressive effect of meal timing was related to increased activity of specific genes, such as tumor suppressor genes. The researchers suggested that this effect is related to reinforcement of circadian rhythms in the mice by meal timing.

The study grew, in part, out of observations that employees on a work schedule that is outside of normal hours (shift work) tend to show an increased risk of developing breast, colon, or prostate cancer. Although more research needs to be done, the French study is intriguing.


  • Li XM, Deleunay F, Dulong S, et al. “Cancer inhibition through circadian reprogramming of tumor transcripome with meal timing,” Cancer Research (April 2010) : Vol. 17, No. 8, pp. 3351-3360.

More Followers than Beyoncé, and Even Hotter

BeyonceWe’re talking about the sun, at 27 million degrees F at its core, or 15 million C. And those followers are sunflowers. They bend towards the sun as it rises in the east, and follow its path until it sets in the west. At night they bend back, and face east again, to continue their daily ritual the next morning. Now we know how they do it, and perhaps why, too. Story here.


How does your vision affect your mood?

Age-related Macular Degeneration

Age-related Macular Degeneration

A study from Denmark shows being blind or visually impaired increases your risk of seasonal affective disorder.

Vision and Seasonal Affective Disorder: An Interview with Helle Madsen, MD

Helle Madsen, MD, of the Mental Health Services Copenhagen, University of Copenhagen, Denmark, recently presented a poster at the American Psychiatric Association’s annual conference in Atlanta, Georgia, USA. CET asked Dr. Madsen a few questions about her findings.

CET: Dr. Madsen, you and your colleagues recently reported that seasonal affective disorder (SAD) was extremely common in people who are visually impaired.

Dr. Madsen: Yes, we found that totally blind people were twice as likely to have SAD as the average person, and people who had greatly reduced sight were three times as likely to have SAD.

CET: Why is that?

Dr. Madsen: Light striking the retina directly affects mood, and circadian rhythms. In persons with severe visual impairment, the pathway of light input is interrupted in varying degree so that not enough light reaches the brain to maintain normal mood and energy levels. Studies in SAD patients suggest that their retinas are less sensitive to light. This subsensitivity has been shown for both rods and cones, and the intrinsically photosensitive retinal ganglion cells.

CET: How did researchers find that out?

Dr. Madsen: We looked at people who had problems with vision early in life, including individuals who are born blind. These individuals with early vision problems had fewer symptoms of SAD than people who develop eye conditions later in life.

The retina

The retina has with two types of photoreceptors for vision: rods, which cannot detect color, and cones, which can. Courtesy of the National Eye Institute, National Institutes of Health

CET: Why is that?

Dr. Madsen: We do not know, but we hypothesize that the brain sets the threshold for necessary light input at a lower level if you are born with an eye disorder. This effect makes visually impaired persons born with normal sight vulnerable to SAD ― more vulnerable than they would be if their visual systems had only been exposed to lower light levels in the first place.

CET: Any other findings?

Dr. Madsen: We also discovered that people with macular degeneration ― which starts with blurred or no vision in the center of the visual field ― have increased symptoms of SAD.

CET: Would these individuals, or anyone with visual problems, benefit from light therapy if they had seasonal affective disorder?

Dr. Madsen: We don’t know, but it is very possible. Our findings suggest that they are still somewhat sensitive to changes in light conditions, and therefore possibly able to benefit from light therapy. I also think it is important to inform persons with visual impairment of the importance of increasing their light exposure as much as possible during winter. It they are not too photosensitive, they should open their eyes, and not wear sunglasses when outdoors.

CET: What implications might your work have for how health professionals treat people with visual impairments?

Dr. Madsen: If a person presents with depressive symptoms in relation to a complete or partial lack of sight, I think it is important to consider whether there is a seasonal pattern and if so increase light exposure and attempt light therapy.

CET: Thank you, Dr. Madsen

Interview edited for CET.

Spotlight on Parkinson’s Disease

Light therapy, once typecast as the treatment for seasonal affective disorder (SAD), continues to increase its therapeutic repertoire. Last year, it beat Prozac (fluoxetine) hands down in an elegant study of major depression. (For details, download’s free Light Therapy for Major Depression: A Game Changer.)

This week, in a randomized controlled trial, light therapy continued to show its potential in the treatment of Parkinson’s Disease. Parkinson’s, one of the most common neurological disorders, is a progressive movement disease characterized by tremor, rigidity, stooped posture, and difficulty walking. Often, impairments in sleep and alertness accompany the disorder.

Bright light therapy was significantly associated with several improvements in the sleep/wake cycle, including a reduction in excessive daytime sleepiness. Other noteworthy benefits in the group receiving bright light therapy (vs the controlled light condition) include fewer overnight awakenings, better sleep quality, and greater ease in falling asleep.

In addition, average physical activity, as measured objectively, increased.

This study is not the first investigation of the use of light boxes for Parkinson’s. However, it makes a significant contribution to a growing literature documenting the power of the inner clock and circadian rhythms to influence the success of medical interventions. It also raises the question of whether light therapy might reduce the motor, as well as the sleep, deficits of Parkinson’s.

Birgit Hӧgl, MD, an expert on sleep and circadian rhythms, praised the design of the research, and said the investigation “sets a new standard for future studies of sleep, wakefulness, and daytime function in Parkinson disease and we hope other diseases as well.”

Original Paper and Accompanying Editorial

Videnovic A, Klerman EB, Wang W, Marconi A, Kuhta T, Zee PC. Timed light therapy for sleep and daytime sleepiness associated with Parkinson Disease: A randomized clinical trial. JAMA Neurol. Published online February 20, 2017 PLUS Editorial

Investigation on the Broader Effects of Light Therapy on Parkinson’s Disease

Willis GL, Turner EJ. Primary and secondary features of Parkinson’s disease improve with strategic exposure to bright light: a case series study. Chronobiol International 2007;24:521-537.

Cannons: Alarm Clocks for Sluggards

benjamin-franklin-portrait“Oblige a man to rise at four in the morning, and it is probable he will go willingly to bed at eight in the evening,” wrote Benjamin Franklin before we knew how to reset our inner clocks.

Franklin was concerned about the waste of candles in Paris while he was living in France as an American delegate. From his perspective, Parisians never woke before noon, and they stayed up late.

Combining genius with his trademark frugality, Franklin proposed what might be considered a Super Duper Standard Time gradually spread throughout the year. Mornings would start with church bells, and, if necessary, cannon to serve as an alarm for sluggards. Guards would stop the passage of optional traffic after sunset.


In addition, Franklin suggested other conservation measures, such as a tax on every window with shutters that kept out the sun. By his calculations, shown in a letter he penned in 1784, his suggestions could save Paris more than 96 million livres tournois a year by conserving tallow.

Recently, Massachusetts breathed new life into Franklin’s idea. Find out why this corner of the United States wants to swap time zones. Story here.

Naps and Apps: The Ticket for Jet Lag?

Naps sometimes get a bad rap. If you take them shortly before bedtime, you may make it harder to get to sleep for the night. This is probably because sleep pressure, in the form of adenosine, builds up during the day. When you take a nap after dinner, that sleep pressure disappears.

However naps―and a new, free app that makes lighting recommendations when you travel―can help. These ideas may be just the ticket to combat jet lag.  Story here.