A Guide to Bright Light Therapy

What is bright light therapy?

Full spectrum light therapy uses specialized bright, artificial lighting to treat SAD or to provide a daily dose of sunshine for those who don't spend enough time outside under natural sunlight.

What is light therapy used for?

The most common use of light therapy is to treat SAD, a type of seasonal depression during the fall and winter caused by a lack of sunshine. But you don't need to suffer from a clinical diagnosis of SAD to enjoy the stimulating benefits of bright light therapy: think of bright white light as a vitamin to be taken each day for optimal health and wellness! 

1) Treatment of SAD/winter blues

SAD (seasonal affective disorder), aka the winter blues, is characterized by feelings of depression that begin as soon as daylight hours diminish during the fall and winter.

        Common symptoms of SAD are: 

    • Feeling depressed and hopeless
    • Feeling low in energy, sluggish, and agitated
    • Sleep disturbances
    • Difficulty concentrating

        What causes SAD? 

Without enough of the bright white light exposure needed to stimulate the hypothalamus, a part of the brain linked to our body's internal clock controlling the sleep-wake schedule, our body may increase its production of the sleep hormone melatonin while decreasing the production of serotonin, the feel-good brain chemical that helps regulate mood. Light therapy helps reset the internal clock, offering those suffering some relief from their symptoms. 

2) Light deprivation

As we mentioned above, bright light is a necessary "vitamin" for our body - you don't need to suffer from a clinical diagnosis of SAD to enjoy the stimulating benefits of bright light therapy! 

Just as in its use as therapy for SAD, light therapy can help prevent issues associated with lack of sunlight: without the presence of bright light early each day, our body has a difficult time waking up in the morning, staying alert throughout the day, and falling asleep at night. 

For those who are indoors when the sun is out, you will benefit greatly from supplementing bright light through light therapy every morning that you aren't outside in the sun.

3) Depression

We hope you see the trend here; light therapy helps regulate mood and energy and keeps our bodies running smoothly! 

Since bright light is stimulating and helps regulate our hormones/neurotransmitters, it isn't a surprise that studies suggest light therapy can be helpful for those suffering from bouts of depression - even if not seasonally related. Specifically, as mentioned before, bright light affects the up-regulation of serotonin, the neurotransmitter related to mood/happiness and well-being.  

How does light therapy work? 

So we've spoken about its uses, but how exactly does light therapy work? We've briefly touched on the effects light therapy has on the body, i.e., how it affects mood, hormones, sleep, etc. Now let's learn how it causes these effects. 

It all starts with blue light

What do we mean by blue light? Well, it may be helpful to see a diagram of the full electromagnetic spectrum and the visible light spectrum that lies within. 

diagram of electromagnetic spectrum

To understand how light affects us, it's important to understand that all electromagnetic energy - visible light or other - has a wavelength and corresponding energy. 

As reflected above, as we move up the spectrum, wavelengths get shorter and more energetic. It's precisely the higher part of the visible light spectrum - blue light - that noontime sunlight is comprised mostly of. 

10,000 lux: bright blue light

Blue light on its own may be full of energy, but to trigger a significant biological responses in our body, we need a lot of it; it must be bright enough for our body and eyes to pick up on. 

In terms of brightness: what exactly do we need? You undoubtedly have already seen the answer everywhere: 10,000 lux. Lux, pronounced (lucks), is a unit of illumination. The higher the lux, the brighter the light source. For reference, daylight on an overcast day at around noon is around 1200 lux. 

Our eyes: a window to the soul and our master clock

Our eyes are constantly taking in information from the environment around us. Perhaps surprisingly, not only do eyes allow us to see, but they also reserve a part of their ability for non-visual tasks, such as determining how much light is in our environment! 

Our eyes detect the presence of light through specialized non-visual photopigments called melanopsin (a light-sensitive retinal protein). Melanopsin is most reactive to shortwave blue light, which, if activated by the presence of light, sends off a signal to our brain's hypothalamus. Within the hypothalamus, lies a cluster of cells (called the suprachiasmatic nuclei, or SCN) whose job it is to coordinate our daily cycles of behavior and physiology with our external environment. 

In other words, our circadian rhythm (master clock) runs internally, but responds and adapts to our external world. The circadian rhythm runs in a cycle of approximately 24 hours, and apart from controlling our sleep/wake schedule, controls other biological processes such as the timing of hunger, digestion, body temperature, and the release of hormones to control energy throughout the day. 

Kinds of light therapy

Now that we know more about the workings of light therapy, how does one go about choosing a device to get their daily dose? Here are some criteria to help in your decision.

Lux: As mentioned before, your unit should be able to provide 10,000 lux of light. Most units have gradual brightness settings, with 10,000 lux as the highest level. 

Now, let's decide on the form: 

Light Pads

Available in different sizes, most popular are light therapy "pads" similar in size and appearance to a kindle or iPad, or you might find replaceable light "box" units where you switch out the bulbs.

Light Boxes

No longer as popular due to the availability of LED, Lightboxes may be larger than light pads (most measure 2 feet in diameter), but their practicality lies in their lifespan: one box should last a lifetime - provided that you change out the light bulbs as needed! Also, for those of you who prefer a DIY method, being able to change out the bulbs is great; it allows you to change bulbs as they begin to dim naturally over time, and allows you to choose whether you use an LED or fluorescent light source.

LED vs. Fluorescent Light Therapy

The most common light technology used for light therapy these days is LED. 

The unfortunate thing is many suffering from SAD also have some range of photosensitivity. For many, LED doesn't sit well with their physiology. We wish we could send you on your way with incandescent or halogen light bulbs, but those options aren't "blue" enough to serve as true light therapy. Full spectrum fluorescent light therapy is your best bet. 

Can't I just use full spectrum or daylight light bulbs? 

It won't hurt, but to rely on light bulbs alone will leave you wanting more. A common misconception is that a full spectrum light bulb serves as light therapy on its own. Light therapy uses full spectrum lighting but at a very bright intensity.  We wrote up a whole article that goes more into detail about whether you can use full spectrum light bulbs for SAD. We highly recommend reading it! The same goes for daylight bulbs - which, by the way, say nothing about a light's quality or fullness of spectrum. Daylight bulbs usually only refer to color temperature (about 5000-6500K) That might be the blue white light we need for light therapy, but again, light bulbs on their own won't cut it. 

Of course, Full spectrum bulbs such as Chromalux help so much with well-being and have many other awesome benefits (like nourishing infrared) over standard, general-use light bulbs. Definitely use them in conjunction with your light therapy sessions for maximum benefit!

How to use light therapy

Use your light therapy device in the morning

Light therapy is most effective when used in the morning. (You don't want a bright dose of blue light keeping you wired through the evening)! 

Keep it on the kitchen counter or on your desk at work in the morning.

Place up to 2 feet away from you, to your side

Your light therapy manufacturer can tell you exactly how close you should be to your device to get benefits, but a general guideline is about 2 feet. 

Let the light shine into open eyes, but don't look at it directly!

The most important thing is for light to reach your open eyes. If you work using blue light filtering glasses, you'll want to take those off while using light therapy for the most effective dose. 

Try for 20 minutes at first to see how you respond; you should begin to feel a sense of alertness. If you start feeling jittery, that's an indication to place your unit a little further away or use it for less time. You'll soon learn how your body best responds, and your needs may also change over time!

Closing Thoughts

Well, that, in a nutshell, is bright light therapy. If it's not already part of your wellness toolkit already, we hope you'll consider adding it!

And, if you're a seasoned user, we hope you were able to glean some useful information from this article! 

All the best in light and health!