The CET Blog

Sunlight Is the Best Medicine

Pioneering nurse Florence Nightingale was rigorous not only about kindness and cleanliness—she maintained meticulous statistical records about her patients to determine the most effective treatment practices.

Florence Nightingale

Source: Wikimedia

In addition to encouraging good ventilation, promoting adequate sleep, providing a nutritious diet, and allowing plants and flowers in the sickroom (she knew that they provide oxygen and consume carbon dioxide, as well as provide a pleasant focus), Nightingale was an enthusiastic proponent of allowing as much natural light into the patient’s room as possible.

As she wrote in Notes on Nursing, “It is the unqualified result of all my experience with the sick, that second only to their need of fresh air is their need of light…And that it is not only light but direct sun-light they want.” She knew that her patients in rooms facing east recovered more quickly than those in rooms facing other directions—or in windowless rooms. She observed her patients turning their faces toward light and compared them to plants following the sun in its course across the sky. We cannot be sure whether this light acted as a mood and energy enhancer in the hospital room or also contributed to ridding of her patients’ infections or other disease processes. But her realization was perspicacious and foretold of light therapies, in various forms, that continue in active development.

National Jewish Hospital

Source: wikipedia

Similarly, before the development of antibiotic therapy for tuberculosis, sanatoriums addressed the worldwide pandemic with sunlight. Doctors noted that patients who lay in the morning sun gained more weight and went home sooner. This became standard practice around the world:

  • In 1903 Swiss doctor Auguste Rollier opened his “sunlight clinic,” which featured an enormous solarium on the roof and developed a slow, careful tanning process for new or especially feeble patients. Here, the ultraviolet (UV) component in sunlight, acting on the skin—now understood as carcinogenic in high doses—was the presumed mode of action, although the patients may also have benefitted from the mood and energy boosts of light to the eyes.
  • Deep in a Finnish forest, in 1929 architect Alvar Aalto built a sanatorium that prioritized access to natural light, enabling patients to benefit from the sun while resting comfortably in their rooms. Light through the windows would have substantially reduced UV exposure, and the benefit of such filtered light to the eyes seems likely to have involved the mood-energy effect.
  • In the early years of the 20th century, my great-grandparents ran a tuberculosis sanatorium in the beautiful town of Otwock, Poland. The air was clear, the climate was sunny, and the patients—when they weren’t eating one of their eight daily meals—spent their time lying quietly in the sun, well bundled up in autumn and winter. Bundling up outdoors in fall and winter, when UV levels from skylight are lower than in spring and summer, again imputing mood-energy enhancement mediated by visible light.

What Nightingale observed more than a century ago, modern science has now proven. Sunlight reaching the eyes can reset a person’s circadian rhythms, enabling a healthier sleep-wake cycle and better healing. And it can be deployed strategically to treat mood disorders in particular. Don’t take my word for it—here’s some more recent evidence:

  • Pioneering chronotherapist Francesco Benedetti and his colleagues found that patients suffering from bipolar depression who were placed in rooms with an eastern exposure with earlier morning sunlight recovered almost four days faster than patients whose rooms had a western exposure. Similarly, another study found that patients admitted to two hospitals for depression—one with sunny rooms, one with darker rooms—stayed approximately three days less if they were in the sunnier rooms.
  • Benedetti also demonstrated that artificial sunshine from light therapy lamps can be an effective, non-invasive, and safe intervention for bipolar depression, which can be difficult to treat with antidepressants, and their hit-or-miss effectiveness for individual patients. The risk of triggering a manic or mixed episode of the disorder was very low, certainly no higher than with the drug therapies.
  • A 2013 study of patients with cystic fibrosis and co-morbid depression suggested that exposure to light significantly improved patients’ chance of depression remission.
  • A review of hospital admissions in Egypt, a country with year-round sunshine and a fairly stable climate, showed more admissions for depression in December, and more admissions for mania in June. In contrast, schizophrenia admissions did not vary by season. This is consistent with a large body of research that suggests that bipolar disorder is a circadian rhythm disorder.

A modern heir to Rollier and Aalto is Dr. Richard Hobday, who is what the British call a “chartered engineer.” I might not recognize that term, but I’m impressed by his research and practice. Hobday’s book, The Light Revolution: Health, Architecture and the Sun, delves into the history of how sunlight has been used to alleviate conditions ranging from rickets to heart disease. He advocates “5 Points of Solar Architecture for Health”:

  1. Orient the building for sanitation and sunbathing.
  2. Position the rooms for sunlight therapy and disinfection.
  3. Put windows in more than one wall to let the sun in at different times of the day or year.
  4. Ventilate naturally.
  5. Underfloor heating.

As I prepare for a surgery in the spring (once the winter burden of SAD has passed), I’m definitely going to ask the hospital if I can be placed in a room with an eastern exposure. And after I go home, I’ll be sure to spend plenty of my recovery time relaxing (well-sunscreened) in Central Park, soaking up the healing sunlight.

Abigail Strubel

Source: Abigail Strubel

Abigail Strubel, MA, LCSW, CASAC is a Columbia-educated clinical social worker and ​certified alcohol and substance abuse counselor. She uses light therapy to cope with her seasonal affective disorder, and also manages chronic insomnia through acupressure and good sleep hygiene. She has worked with formerly homeless adults, ex-offenders on parole, recovering heroin users, and other interesting populations. Abigail’s posts at the Center for Environmental Therapeutics fuse humor with practical insights about mood, sleep, and alertness.




Terman, M., & McMahan, I. (2013) Reset Your Inner Clock: The Drug-Free Way to Your Best Ever Sleep, Mood, and Energy. New York: Avery/Penguin Random House.


Escape the Burden of Switching to Daylight Time

Our inner clock doesn’t know that the government has rescheduled our lives.

Michael Terman, PhD

Just when you are used to Standard Time, the annual return to Daylight Time arrives. Here, Michael Terman, PhD, warns us of what to expect the next time we need to adjust our clocks.

It happens every year around this period. Those clock faces with arrows on the TV news. The abrupt time change on the cable box and the cellphone. The more gradual changes as you try to remember to reset all the clock-like devices around the house. The forgotten alarm that goes off an hour earlier than you expected. And which button do you push to reset the dashboard clock in the car?

The annual springtime return to Daylight Time—which happens this year at 1 a.m. on Sunday, March 9—may seem to be just one more of those minor inconveniences of modern life.

But is it so minor? According to a recent study published in the New England Journal of Medicine, during the week after the shift into Daylight Time, the rate of hospital admissions for heart attack rose by as much as 10 percent. Another recent study compared high school students in parts of Indiana that use Daylight Time with those in other parts of the state that stay on Standard Time year-round. On average, those who were subjected to Daylight Time had SAT scores more than 16 points lower than those in areas that didn’t shift the clock!

Why? The simplest explanation is that the shift confuses the circadian clock in the brain. This inner clock relies on timed exposure to light, especially natural light, to keep itself in sync with the daily cycle of 24 hours. But the sun doesn’t “spring ahead” on March 9, and neither does your inner clock.

Let’s say your daily rhythm is going to sleep at 11 p.m. and waking up at 7 a.m.. If you live somewhere near the middle of the continental US, that means that during the first week of March, while you’re still on Standard Time, you wake up to find the sun is already up. So far, so good. But come Monday, March 10, when you get up as usual at 7 a.m., it’ll still be dark out for another half an hour or more. You’ve lost an hour of sleep, and your daily rhythm of energy and mood lags an hour behind where it usually is.

To adjust to this, you have to It happens every year around this period. Those clock faces with arrows on the TV news. The abrupt time change on the cable box and the cellphone. The more gradual changes as you try to remember to reset all the clock-like devices around the house. The forgotten alarm that goes off an hour earlier than you expected. And which button do you push to reset the dashboard clock in the car?

The annual springtime return to Daylight Time—which happens this year at 1 a.m. on Sunday, March 9—may seem to be just one more of those minor inconveniences of modern life.

The loss of an hour in March is hard on a lot of people. It is particularly hard on those who are battling winter depression. After March 9, according to the clock, sunrise will come as late as it did at the end of December, during the darkest days of the year. Sure, we also get an hour added on at the end of the day, but that’s no help. It is early morning light that our inner clocks rely on to keep in sync with the external world.

Can we do anything to make this transition easier? Well, yes, we can—but it means thinking ahead. The key is to be proactive. Make the adjustment ahead of time. Help the inner clock accommodate to the change gradually, before it happens. In a nutshell, that means waking up and turning up the lights 10 minutes earlier each day for the six days prior to the time change.

That means making a correction of a full hour, plus the daily correction of 20 minutes or so. Not so easy, especially when the morning light that helps you do it doesn’t show up until an hour later. Most of us need a week or more to adjust, and some researchers suggest that our clocks never fully adjust to Daylight Time.

During the week before Daylight Saving Time in early March, and Standard Time, in early November, follow us on Twitter (or @mychronotherapy) to receive daily reminders and news about how to best adjust to losing, or gaining an hour.

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.


This Is Why Street Lights Can Be the Worst Idea in the World

Now an estimated 300,000 million street lights brighten the world.

Street lights create unintended consequences. For example, during the French revolution, they were convenient spots to hang aristocrats. A mob’s cry, “À la lanterne!” was fatal.

Today, street lights have different unintended consequences. They are less dramatic, but more far-reaching, than the murder of aristocrats in Paris.

Mixing Day and Night

Many of us get artificial light at night from street lights. This light suppresses the secretion of the sleep hormone, melatonin.

Newton (1643-1727) shone white light through a prism, and found a spectrum.

Further, this light, while white, includes the blue part of the spectrum. This part of the spectrum energizes us.

 Thus, exposure to light at night makes it is hard to sleep, and weakens our natural circadian rhythms.

The paltry amount of sun most of us get during the day adds to the confusion of our inner clock.  We usually feel we are getting enough illumination when all the lights are on inside our homes and office buildings during the day. However, even then we average much less exposure to light than we would if we were outside on a cloudy day.

Getting the wrong amount of light at the wrong time puts us at risk for insomnia, problems with alertness during the day, and so on. So while street lights serve many useful functions, they also confuse the timing and coordination of many functions, from sleep to digestion.

Shirking the Night Shift

Dr. Knop and her colleagues found that cabbage thistles in lit (vs dark) fields had 13% fewer fruits.

Too much light at night is a problem for other living things as well, as Eva Knop, and her colleagues from the Institute of Ecology and Evolution at the University of Bern, demonstrated in August 2017. They added the equivalent of street lights to five fields, and kept five fields naturally dark. They then compared the nocturnal pollination in the two groups of fields.

When the moths, and other insects, were in fields with lights at night, these nocturnal pollinators were far more likely to ignore their pollinating responsibilities. Specifically, nocturnal pollinators were about two thirds less likely to visit the flowers in the meadows with artificial light. This decreased the fruit set, and hence the reproduction, of plants.

“The pollination during the day obviously cannot compensate for the losses in the night,” notes Dr. Eva Knop.

These findings are serious because:

  • light emissions are increasing as residential areas increase worldwide
  • daytime pollinators, such as bees, are decreasing worldwide
  • it appears that nocturnal pollinators indirectly aid daytime pollinators, so a loss of nocturnal pollinators would have a ripple effect.

The Bottom Line

While artificial light can be a blessing, we are just beginning to see, and understand, a new kind of unintended consequences. Unfortunately, these consequences may snowball as we become increasingly urban, while still living in an interdependent web of existence with insects, and plants.

Related Reading

The Danger of Mixing Day and Night

When the Light You See Is Not the Light You Want

New York Teenager on California Time

Did Jonathan do drugs? Did he suffer from anxiety? Did he have attention deficit hyperactivity disorder (ADHD)? While his teachers didn’t know what was wrong with Jonathan, age fifteen, they did know his tendency to fall asleep in their classes was a problem.

Jonathan’s parents were baffled, too. But when Jonathan consistently wouldn’t get up in the morning, his father decided Jonathan didn’t really want to get up. His mother, on the other hand, would sometimes baby Jonathan, and sometimes try tough love. For a while, when he was young, she would sleep in his room, because her presence soothed him. Later, she would leave him alone to cry himself to sleep at night, or pick him up out of bed, and put his feet on the cold bathroom floor, to wake him up for school in the morning. Indulgent or strict, either way, she wound up feeling guilty, and worried she was doing the wrong thing.

But the culprit in this case was not Jonathan’s mother, but Jonathan’s sleep pattern. And the mystery inched closer to a solution during one lazy summer vacation after Jonathan’s parents divorced. Without obligations to keep Jonathan on a schedule, his mother thought, “I wonder what kind of sleeping timetable Jonathan would have if I didn’t try to make him go to bed, and get up, at particular times.”

The results of her experiment surprised her. For the first week, Jonathan slept from 1 AM to 1 PM. That was followed by a second week of sleeping from 2 AM to 2 PM, a third week of sleeping from 3 AM to 3 PM, and so on. Thus although teenagers need a great deal more sleep than adults, Jonathan needed a great deal more sleep than even the average 9.2 hours per night that most adolescents require. But why was Jonathan naturally gravitating towards later and later bedtimes?

Jonathan and his mother found out by chance, when they saw an article about sleep and circadian rhythms in The New York Times. The article was by psychologist Michael Terman, a pioneer who applies research about the body’s natural rhythms of activity to everyday problems.

When Jonathan and his mother visited Dr. Terman, he gave them very specific advice about how to use light therapy to reset Jonathan’s cycle of sleep and wakefulness, and continue to use a small amount of light therapy daily to stay on a good schedule. Specifically, Dr. Terman gradually adjusted Jonathan’s bed-time from the wee hours of the morning to an evening hour that was more in tune with his family, friends, and school. Then Dr. Terman showed Jonathan how to maintain this schedule with light therapy and structured time.

Resetting one’s internal clock is more of a challenge than it sounds, but it was necessary because, as Dr. Terman put it, Jonathan was physically in New York, but his circadian rhythm was three hours behind, on “California time.”

New York


The effects of light therapy for Jonathan were striking. Jonathan reports that this simple, non-intrusive intervention enabled him to stay awake in all his classes, and enjoy an improvement in his grades. This treatment also gave him a sense of control over his therapy, since he felt that if he took medication, he would be dependent on pills. On the other hand, the light box fascinated him.

Jonathan’s ownership of his problem made his mother proud of him, but her real satisfaction with treatment lay in the results. Before light therapy, she said, Jonathan was like a drooping plant that hadn’t been watered for a long time. Resolving his sleep problem was like watering that plant, like bringing half-dead leaves to life in Louisville, Kentucky. It was solving the problem of the New York teen on California time.


More Information on Common Problems with Falling Asleep

Sleep Smarter at Any Age: A Free App and Three Tips

Why Seniors Have Sleep Problems and How to Fix Them

Search Sleep Phase Delay, Sleep Phase Advance, and other sleep topics in Ask the Doctor.


A Tale of Two Sleepers

How a champion sleeper and an insomniac learned to synchronize their sleep schedules.

A Tale of Two Sleepers

It was the best of sleep, it was the worst of sleep—in the same apartment and the same bed. Abigail’s co-worker Clara and her partner, Javier, grew up in the same neighborhood and fell in love after college. It wasn’t until they moved in together that they discovered they had radically different sleep behaviors and attitudes. Could a sleep pattern established during childhood be changed to eliminate adult insomnia? Spoiler alert: unlike Dickens’ tale, this story has a happy ending.

Clara is a policy analyst at the city agency where I work. She’s known her partner, Javier—who goes by “Javi”—since childhood. “We grew up in the same neighborhood in Queens, and we were in the same after-school program for years as kids,” says Clara. “We were friends in college, and eventually we started dating.”

Falling in love with the boy next door sounds almost like a fairy tale. Reality hit after they moved in together. “Javi liked to stay up very late, and had a terrible time getting up in the morning,” remembers Clara, who usually goes to sleep by 11:30 pm. “Sometimes he was up because he couldn’t fall asleep, and sometimes he’d fall asleep but wake up a few hours later and not be able to fall back asleep.” (As a fellow sufferer of terminal insomnia, I could definitely relate.)

Javi likes reading in bed, which Clara appreciates. “Sometimes he reads to me and I fall asleep,” she sighs. “It’s kind of like when my mother read to me when I was a child. But she did voices; when she read the Fudge books by Judy Blume, she’d do her ‘fudgey’ voice.” Javi reads Clara the serious literature he enjoys, from a stack of scholarly biographies and histories on his side of the bed.

How does she fall asleep so quickly? wonders Javi

“On my side, I have four or five books that I’ve never finished,” admits Clara. “I get into bed and read a few pages, and then I fall asleep.”

Clara believes her parents successfully trained her to sleep well.

“I remember climbing up onto my dad’s recliner chair so I could nap on his chest,” recalls Clara. “He started napping with me when I was a tiny infant, and it must have continued until I was three or four.” As Clara grew, she continued to associate sleep with a sense of “happy coziness,” she reminisces with a contented, faraway look. “I was a shy kid, kind of a loner, so I was never afraid of being alone, and since I loved sleeping, I never minded going to bed.”

baby and dad sleeping

Clara’s mother reinforced good sleep hygiene with strict bedtimes that increased incrementally as Clara grew up: 7 pm at age 7, 7:30 pm at age 8, 8 pm at age 9, and so on until Clara was a teenager.

“Even as a teenager, I still used my bed just for sleep,” she says. “I remember being told that if you do your homework on your bed you’ll associate your bed with work, so I did my homework on the floor of my bedroom or the dining room table. In college, too—I never studied on my bed. The only time I read in bed is Saturday morning; it’s a nice, slow way to wake up.”

And Clara developed a special technique to help herself on nights when sleep eluded her. “When I was very small, I developed this image in my head of a bookshelf with rows of books in order—like the ‘Harry Potter’ or ‘Baby-Sitters’ Club’ series. Each book had its own topic, like playing with friends, and I’d think about that topic as I drifted off. Sometimes now if I have something on my mind, like a recurring thought, I ask Javi for a topic. He suggests things like dinosaurs” (which didn’t work) “or going to a Mets game” (which had happy childhood associations and helped soothe Clara to sleep).

Clara's Sleep Library

Clara’s Sleep Library













The good sleep hygiene instilled by her parents and refined by Clara herself enables her to wake up refreshed and happy almost every morning. “I still love napping, too,” she confides. “On the weekends I’ll nap.”

Javi’s story was quite different. “Javi’s parents like to stay up late. If my parents stay up late, they end up falling asleep in front of the TV. But Javi’s mom—she didn’t like going to sleep. Javi thinks she influenced how he feels about sleep—like going to bed means you’re going to miss out on something. We blame our moms for everything, don’t we?”

Regardless of fault, Javi couldn’t understand how easily and quickly Clara could go to bed and fall asleep. “He would stay up if he didn’t feel physically tired—he’d say, ‘I didn’t work out today’ or ‘I slept late today.’ He didn’t think of sleep as a habit—more of a response to activity (or lack of activity).”

Javi tried reading in bed, but found that even the driest of academic tomes couldn’t lull him. He switched to popular fiction like spy novels or detective procedurals. When those failed, he turned to silly books like collections of “Garfield” cartoons. Still, he struggled to fall or stay asleep—and struggled even more the next morning to wake up.

Napping on Clara’s father’s chest wasn’t really an option, even though both sets of parents still live in Queens. So Javi did the next best thing: he adopted Clara’s sleep schedule.

“He made a New Year’s resolution to try to sleep better,” says Clara. “Now during the week he goes to sleep when I do, whether he feels tired or not. I usually fall asleep faster than he does, but he’s falling asleep faster than he used to and not waking up as much.” Javi still stays up late on weekends—for optimal sleep hygiene, it’s recommended that you get up and go to bed at the same time every day of the week. But his sleep pattern during the week has become much more regular and restful.

A Tale of Two Sleepers

Credit: Vera Kratochvil/public domain

It is a far, far better sleep that he sleeps, than than he has ever slept. It is a far, far better rest that he goes to than he has ever known.

Abigail Strubel


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.