Natural light streams in through the Henry A. Jordan M ’62 Medical Education Center’s many windows.
Many buildings today incorporate much more glass and natural light into their design than in the past. For example, Penn Medicine’s Henry A. Jordan M ’62 Medical Education Center and the pavilion, currently under construction, both feature entire walls of windows that let in natural light. While this is clearly an aesthetic choice, it’s also a healthy choice. A.
Our circadian rhythms (i.e. our internal clocks) require exposure to full-spectrum natural light to stay in sync with the external environment. Natural light is made up of several wavelengths, each a different color. Red is the longest; shortest violet. When all the waves are seen together, they produce white light.
“Light is our greatest temporal marker,” said Annika Barber, Ph.D., postdoctoral researcher in chronobiology, but “blue light is particularly important”. Special cells in our eyes use melanopsin, a pigment particularly sensitive to blue wavelengths, to transmit information to the suprachiasmatic nucleus (SCN), a part of the brain’s hypothalamus responsible for controlling the circadian rhythm. “Light input resets the SCN daily, telling the brain: It’s morning!
As the primary pacemaker of the heart, the SCN then “communicates” this signal to all tissues in the body so that they can be synchronized and perform their functions at optimal times of the day. “It is important that all of our internal clocks show the same time. This is how we anticipate daily changes in our environment,” Barber said. Without daily exposure to natural light, health problems can develop, including reduced attention span, depressed mood, and possibly weight gain. “Even if you exercise and eat the same amount, if there isn’t a strong light stimulus that resets your body’s clocks, your metabolic clock may be out of whack and not process the food you eat as effectively…resulting in inappropriate fat storage.”
A person needs at least 30 minutes at 1000 lux (light metering mode) to start the circadian process, which is quite easy to get out of. Although sunlight levels vary, in the morning sun you can get up to 100,000 lux! But even on an overcast day, you get 1,000. If driving or walking to work isn’t part of your daily commute, working near a window (or within 20 to 25 feet) will also provide the exposure required.
Regardless of how you choose to get your lux, it’s important to note that the best way is from a natural source. Most fluorescent lights do not include the blue wavelength, which triggers the daily wake-up call. Using a light meter, Barber measured three locations in his workspace. The light falling on the windowsill measured 5,000 lux. On a desk by the window it fell to around 700 lux, but in an office with only fluorescent light the meter read less than 250 lux. Barber said that while fluorescent lighting has improved in terms of expanding the wavelengths of light, “when it comes to our circadian rhythm, we’re not quite there.” When you work indoors in low light conditions, you don’t get a normal distribution of light to synchronize your clocks.
Fortunately, our internal clock is “robust,” she says. “It will try to function with whatever you give it. If you go out on the weekend, your clock will be retrained (reset) to normal. This will get you through Monday and Tuesday, but on Wednesday, “you’ll start to feel the slump.”
While access to bright light is essential during the day, getting too much light – especially blue spectrum light – in the evening is problematic. not GOOD. “It’s good that when you leave work, the intensity of the light is less. You want your clock to slow down,” she said, noting that exposure to bright light in the late afternoon disrupts the production of melatonin, which our bodies need to prepare for sleep. This includes artificial blue light emitted by electronic devices – like smartphones, laptops and tablets – which also suppresses the release of melatonin. According to National Sleep Foundation“The more electronic devices a person uses in the evening, the more difficult it is to fall asleep or stay asleep.” Additionally, when used at bedtime, these devices “reduce the total amount of REM sleep and compromise alertness the next morning.” Over time, these effects can add up to a chronic and significant sleep deficit.
For people who don’t have regular access to a window during the day, such as those who work in laboratories or basement offices, there are still ways to get needed light. For example, go out for a 20-minute walk during lunch. Exposure to outdoor light and exercise will do you good! Can’t go out? Have lunch by a window.
Or get a light box, typically used to treat seasonal affective disorder, for your workspace. People living in countries where winter days are very short – and where SAD rates are higher – use this type of therapy to help reverse the impact.
But only use the light box in the morning, Barber stressed. “You don’t want to tell your internal clock that it’s 3:30 in the morning,” she said. “The body will take this as a warning signal… but at the wrong time! »
