Light Therapy
One of the most vital treatments in medicine is sleep regulation, and one of the most neglected components of sleep management is light management. Our brains evolved with many mechanisms to keep us highly functional during the day. At night, our brains don’t stop but they work even harder. They stabilize networks, shape and strengthen memories, and most importantly clean out all of the garbage that builds up during the day. That’s right, our brains are full of waste products and other proteins that must be flushed out through a set of drainage pathways called the Glymphatic system. But this Glymphatic system slows to a trickle when the brain is awake causing those bad proteins to build up slowly over time leading to cognitive slowing, inflammation, and unstable connections. Not only sleep, but deep slow wave sleep, is when those drainage pathways become open and work to clear out the mess.
After the basics of sleep hygiene, scheduling wake and sleep time, one of the most vital ways to improve your cycle is to manage light exposure. Our brains want to see the sun rise in the morning with good light exposure. Especially in the north, this is impossible since we don’t get direct sunlight for 80% of the year. Even in other places in the world, most people work inside with very limited sun exposure. Then, our brains want to see the sunset and get about 4 hours of darkness before we go to sleep. Instead, our modern world is constantly well lit by artificial light, bright screens and light bulbs that tell our brains it is noon all day long. While most people know to avoid blue light and screens before bed, very few people think about how to get the right amount and frequency of light to properly wake the brain up.
Most well studied for mood disorders that worsen during the winter (seasonal affective disorder), light exposure with devices that simulate the frequency and brightness of morning sunlight have shown to dramatically impact mood and overall health. It is presumed that at least a large part of this effect is from its impact on the brain mechanisms responsible for regulating the sleep cycle. The right type and amount of light shining on the back of the eye sends signals to the hypothalamus which are responsible for many balancing mechanisms including hunger, body temperature, and most importantly hormones related to sleep.
While the exposure of sunlight on the skin is clearly therapeutic, helping in the production and processing of many vitamins and other processes, it comes with a careful balance for skin health and cancer risk. However, newer devices that eliminate more harmful components of sunlight, but leave the vital components for the sleep wake cycle regulation have been thoroughly studied to improve mood, energy, and most importantly for neuropsychiatric syndromes, daytime alertness and night time sleep quality.
There are many devices out there that can have beneficial effects. Many of them are screens or lamps that sit on a desk and shine light towards the face. Most of the time when I suggest patients use these, I later find that they aren’t using them correctly. They must be placed a certain distance from the face, usually at an angle so you aren’t looking directly into them, and they must stay there for the duration of the treatment: usually 30-45 minutes. Other options exist including visors and glasses that are more mobile and are foolproof regarding distance from the eyes. I’ve yet to see data to suggest that more expensive glasses are more effective than cheaper desktop lamps, but if you want to be able to get up and refresh your coffee without interrupting the treatment, I find the glasses are likely the best option.
