In the past, before the advent of electric light, people ate their evening meals by candlelight.
When my wife, Clare, and I are in a romantic mood (or when there’s a power outage), we still do that sometimes, although switching on electric lights is of course much more convenient.
But maybe the idea of ??going back to more candlelit dinners will catch on, thanks to recent research suggesting that reducing your exposure to bright light at night can lead to better sleep, an improvement in your blood sugar levels, and even some weight loss. . of weight.
Plus, there’s some evidence that exposure to bright light in the late afternoon and evening can cause anxiety and mood swings in some people (but more on that later).
I’ve written before about the benefits of exposing yourself to bright light in the morning, ideally by taking a brisk 30-minute walk or simply spending some time in your garden.
A couple holds hands by candlelight during a romantic dinner
That’s because it helps reset your internal body clock, which regulates your circadian rhythms, which in turn determines the timing of natural body processes and functions, including your energy levels and your sleep.
But what you do at the other end of the day also matters.
For example, there is growing evidence that exposure to bright light at night not only disrupts your sleep, but can also lead to weight gain.
In a study published in the journal PLOS One in 2016, researchers at Northwestern University in the US took 19 healthy adults and asked them to eat their evening meal in dim or bright light.
When the volunteers ate under bright light, it led to an increase in insulin resistance (meaning their bodies had more trouble getting their blood sugar levels down after they ate the meal).
The researchers said that over time, increased insulin resistance and a buildup of blood sugar can lead to increased body fat, weight gain and a higher risk of type 2 diabetes. And pregnant women may be particularly sensitive to the influence of light; one of the unfortunate potential complications of getting pregnant is that some women develop gestational diabetes, where their blood sugar levels rise into the diabetic range.
In the UK, around one in 20 pregnant women are affected, and while the condition often clears up once the baby is born, if you get gestational diabetes (and are at a higher risk) you are ten times more likely to get type 2 diabetes . of cardiovascular problems and stroke) later in life.
In a study published in the journal PLOS One in 2016, researchers at Northwestern University in the US took 19 healthy adults and asked them to eat their evening meal in dim or bright light (file image)
Gestational diabetes may also affect the baby, increasing the risk of being overweight or having high blood pressure as they grow up. In a recent study of pregnant women published in the American Journal of Obstetrics and Gynecology Maternal and Fetal Medicine, 741 pregnant women were given a wrist device to measure their exposure to light. most bright light exposures in the three hours before bedtime were at the greatest risk of developing gestational diabetes.
This wasn’t a true randomized controlled trial – which involved a placebo group – but it certainly adds to research suggesting that late night light exposure can really disrupt our metabolism.
Dr. Minjee Kim, an assistant professor of neurology at Northwestern University who conducted the study, said all this research on light has had an impact on how she lives her own life.
“I’m the light police at home now,” she says. ‘I turn off unnecessary lamps and try to dim the light as much as possible. You don’t need bright light for evening activities such as dinner and washing the children.’
She also recommends avoiding using your computer or phone leading up to bedtime — “but if you must use them, keep the screens as dark as possible.”
When the volunteers ate under bright light, this led to an increase in insulin resistance (file image)
And as I said before, light not only affects our blood sugar levels, but also our mood.
Too little light in winter can lead to seasonal affective disorder (SAD), also known as the winter blues. As I know from personal experience, you feel depressed, moody, and you crave carbohydrates. Apart from that, too much light in the evening can affect people with Alzheimer’s.
If you have a loved one with this disease, you may have noticed that troubling symptoms such as confusion and anxiety get worse in the late afternoon and evening.
This is called “sundowning,” and a new study suggests it may be caused by changes in light levels.
This behavior was previously thought to be due to changes in the brain, but research in the journal Frontiers In Aging Neuroscience suggests that changes in the retina, the light-sensitive area at the back of the eye caused by Alzheimer’s disease, are responsible. . This understanding could potentially lead to new approaches to dealing with sunset.
In the meantime, Dementia UK recommends closing the curtains and turning on the lights before sunset ‘to ease the transition to night’.
Our distant ancestors rose at dawn and huddled around the campfire at night.
So it’s not surprising that light, how much you’re exposed to and when, has such a profound effect on our minds and bodies.
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