I just watched this video from AsapSCIENCE about what it feels like when you are dying, and one of the things they noted that happens is “seeing light.” Of course, this is also something common in mystical experiences. They explained a possible cause of this phenomenon in NDEs:

At this point studies show that your heart will beat less forcefully, your blood pressure will fall, and your organs including your brain will function less. Essentially your brain is trying to conserve energy as it slowly dies, and this causes your brain to lose the power of inhibition. You may have heard people talking about “seeing the light” or “moving towards the light” during near-death experiences. Brain studies on rats show that a dying brain’s lack of inhibition causes the visual brain system to fire. This has also been found in some human studies as well which may explain why many people report this phenomenon of seeing light as their brain begins to die.

“It’s way different than you think,” AsapSCIENCE, timestamp 1:50

In other words, with reduced blood flow and oxygen supply to the brain, the brain’s function becomes reduced. Normally, the brain inhibits or suppresses certain neural activity, but as the brain loses power, this inhibition is lost. Without the brain’s normal inhibition, the visual processing areas of the brain become overly activated, perhaps extremely so, and this causes a perception of seeing a very bright light. Essentially, the lack of inhibition in the dying brain allows the visual system to “fire off” uncontrolled, leading to the sense of seeing a bright light or moving towards a light.

This disinhibition in the brain’s functions may be the cause of other phenomena in approaching death, as noted in the video, such as out-of-body experience, observing events without pain or distress (being in peace), a meaningful evaluation of one’s life, assessing one’s actions towards others throughout their life, and strange changes in memory, such as accessing very old stored memories, or knowing that they were dying but feeling like they were going “home.”

It is also interesting that in one study, the brain activation while dying was similar to people who were on the psychedelic DMT (found in ayahuasca).

What’s interesting to me is that these phenomena are also present in spontaneous mystical experiences, as well as in the experiences of seasoned meditators. That may point to a common cause in the brain for all of them, this disinhibitory effect, which causes the brain to light up in ways that are normally suppressed or “inhibited,” both in the areas associated with visual perception, memory, and perhaps other areas.

Where I might differ from most approaches to this kind of thing is that many say that this is an impairment of the brain, a malfunction of the brain as it is dying, and is therefore hallucinatory, delusional, and of no value whatsoever; they think that it tells us nothing about the true nature of reality.

I disagree.

I suggest these experiences do indeed decrease the inhibition of the brain’s normal functioning, but this functioning ordinarily hides or veils the deeper nature of reality from our awareness. It is showing us the shadows on the cave wall. It is suppressing our perception of the Real.

The brain has been described as a “reducing valve,” highly narrowing or hiding most of reality from our awareness, or even constructing shortcuts that help us navigate the world but do not show us the world as it really is. But if this inhibitory/suppressing function and shortcuts are deactivated, whether when we are close to death, taking a psychedelic or entheogen, or in deep meditation, then the brain loses this inhibitory ability, this reducing valve functioning, this narrowing, this veiling, this suppression of brain function that may show us the true reality. The veil is pierced, and reality is seen in a more pure way, as it really is.

To give an example of how this might work, consider that the brain normally produces the perception of a subjective “I” and sees all other things or beings in our environment as “other.” This duality function is considered normal and is usually assumed to be reality as it really is. We think that there really is an “I” separate from all other things. But it may also be part of the “inhibitory” functions of the brain, suppressing the true nature of Reality, or perhaps part of a shortcut construction that helps us navigate the world but is a veiling of the world as it really is. The truth may be that we are not actually separate from the universe, but rather it is all One Great Whole, and we are a manifestation of it. So the brain is veiling reality as it really is. This duality we normally perceive is not Real.

As Einstein once said:

A human being is a spatially and temporally limited piece of the whole, what we call the “Universe.” He experiences himself and his feelings as separate from the rest, an optical illusion of his consciousness. The quest for liberation from this bondage [or illusion] is the only object of true religion. Not nurturing the illusion but only overcoming it gives us the attainable measure of inner peace.

See my article “Einstein’s Misquote on the Illusion of Feeling Separate from the Whole“

So Einstein says that the perception of someone’s sense of self being “separate from the rest” of the universe is an “illusion” of the brain, and even possibly a “bondage.” It is not the way the universe really is! Overcoming this illusion/bondage is not only the object of true religion but is what brings what many religious seekers truly desire: inner Peace. We see that we are not merely one particular body, but the Whole manifesting as all bodies, including this one. The “human being” is a particular “limited piece of the whole,” but is still a manifestation of the whole, an Incarnation of it and thus inseparable from it. We are One, and this is Peace.

Decreasing these inhibitory, suppressing, or constructing functions of the brain may thus help to reveal reality as it really is, and cause many of the phenomena of mystical experience that are so profound, meaningful, and life-changing, such as the very bright light and the realization of Oneness or Love. They are not hallucinatory, delusional, or meaningless, but just the opposite. They may be revealing Truth, Reality, and Ultimate meaning, even what some people call “God,” our true home, and that we are that Divine. If we “die before we die,” we may just realize it, the way many mystics in history have realized it. Even the way I have realized it.