Improving the way you feel through small adjustments in your light exposure.
There are many health and fitness behaviours that can, initially, be difficult to start and maintain due to the effort involved.
The following is a behaviour that will have far-reaching benefits on how you feel and function on a daily basis.
It’s easy to implement and doesn’t require much effort (just a bit of awareness).
It’s just a small adjustment in your light exposure.
Depending on what kind of light you’re exposed to (their wavelengths), there are different ways your body responds.
For this blog post, I’d like to discuss one kind in particular, the short wavelength of light. This is the light that appears blueish-white. It’s emitted from most sources of light (including the sun) but there’s also a lot emitted from electronic devices and LED lights.
When this short wavelength of light (blue-white light) enters our eyes, our body has been shown to respond with a reduction in melatonin (a hormone responsible for fatigue and sleep-like promoting changes) and changes to your circadian rhythm (your body’s internal clock that organises a lot of your bodily functions) (1)
The two are intertwined.
When things like your circadian rhythm and hormones are altered, there can be far-reaching effects due to the numerous roles they play in your body!
If you’re exposed to this wavelength of light at the ‘wrong time’, the hormone and circadian rhythm changes that take place can throw things out of whack, and consequently impact your health.
But!
There’s also evidence that if you expose yourself to this kind of light at the ‘right time’, then it can help your mood, alertness during the day, and your sleep at night.
So it’s about knowing when to expose yourself to this kind of light so that there’s a benefit to your overall health and fitness.
It’s pretty straightforward too.
As we wind down for a good night’s sleep, many processes take place within the body thanks to your circadian rhythm and the corresponding hormones that are released. These processes promote good sleep and good health.
Some of these processes, and subsequent changes that take place in the body, include an increase in melatonin (sleep promoting hormone in response to darkness), a lowered core body temperature and heart rate, less alertness and so on ...
If you’re exposed to the blueish-white light discussed above right before bed or during night-time hours (eg. looking at your phone during the night), your body will respond in the following way:
- Lowering of melatonin (2)
- Increase in core body temp (2)
- Increase in heart rate (2)
- Increase in alertness (2)
In other words, the complete opposite to what should ideally be happening at this time.
The light sends the wrong message to your body, and your health can suffer as a consequence.
Many articles/research papers have looked at a specific cohort (HEIJO-KYO). to track them and observe the negative impacts of light pollution/light exposure at night. Obayashi et al., have found the following:
- An association with depression risk in an elderly population (3)
- Potential risk factor for atherosclerosis (4)
- Results in worse sleep including increased wakening, decreased efficiency, shorter sleep time, and taking longer to fall asleep (5)
- Increases the incidence of diabetes (6)
- And in their latest paper, concluded that higher exposure to light at night in the bedroom is significantly associated with obesity, cholesterol issues, body-wide inflammation, sleep disturbances, and depressive symptoms (7)
There is also a lot of emerging research showing disrupted mood regulation and also many studies done on rodents that show exposure to dim light at night results in depressive-like symptoms (8)
*The effects of light exposure at night varies from individual to individual and can depend on a number of factors.
In general, it’s probably not ideal and over time can result in some nasty health consequences. If you want to feel your best, it’s a good idea to reduce light exposure throughout the night and before bed.
- Limit the use of electronic devices around bed time and especially during the night. If you do have to use them, some strategies include dimming the brightness, switching them to ‘night mode’ or darker settings, and wearing blue light blocking glasses.
- Instead of keeping overhead lights on, opt for lamps (eg salt lamps), red lights, or less dim lights that aren’t directly overhead.
- Try to sleep in a pitch black room.
So it’s not ideal exposing yourself to this kind of light at night, but we can use it to our advantage by exposing ourselves to it in the morning and throughout the day!
During the morning/throughout the day, we want these stimulating effects that the short wavelength of light provides. A lowering of melatonin and an increase in alertness, body temperature and heart rate is beneficial during these hours.
It’s sending the right message to our body, that it’s time to get going.
- It can improve how alert you feel and your visual comfort (9)
- If you’re sleep deprived, it can better prepare you for the challenges/demands of your day as it can enhance your ‘Cortisol Awakening Response’ (a response that assists in preparing you for the upcoming day’s demands). (10)
- Studies show that exposure to more of this light in the daytime is associated with better sleep quality (increased evening fatigue, decreased time to sleep, increased sleep quality etc.) (11)
“In sum, research seems to agree that daylight (at high intensities) is beneficial for sleep.” Blume et al., 2019
And what it can do for your mood is also very impressive ...
- Negative mood changes can occur from a lack of exposure to bright light during the day. (12)
- Bright light therapy (daytime exposure to the kind of light we’re talking about) can lead to impressive chronic depression remission rates and is an effective treatment for those who have a depressed mood due to not enough natural daylight exposure (shift workers, elderly people etc.). (11)
(*A one-hour morning walk in natural daylight is as effective as a bright light therapy device)
The best way we can take advantage of the positive effects is to get as much natural light exposure as possible during the morning and throughout the day.
If this isn’t possible, having those bright overhead lights on, being close to a window, and even using a bright light therapy device in the morning/day could be a good strategy to reap these benefits.
For better health (including better mood, better sleep, and a system that’s functioning in its correct ‘circadian rhythm’), expose yourself to bright light (short wavelength of light) at the right times.
In the morning and throughout the day, this is the time to be getting lots of natural light outside, having bright overhead lights on, situating yourself in front of a window when you’re working and so on.
At night, this is the time to minimise your exposure to this kind of light. When you’re sleeping, try to keep the room pitch black. Before bed, turn off the LED overhead lights, dim/night-mode your electronics (wear blue light blockers if you have to), and so you can still see, turn on some dim lamps or salt-lamps around your home.
I’m sure you will notice a difference!
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