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02 Setting / Visual Energy Load and Complete Darkness

Visual Energy Load and Complete Darkness

Darkness is intended to reduce competing visual input and make bodily sensations easier to attend to. Complete darkness is the founder's preference; practical alternatives belong to Sensory Management.

Input, attention, and energy

Vision involves the retina, neural signaling, and cortical processing. Maintaining the electrical conditions for signaling requires energy. But visual input, attention, brain activity, and energy consumption are different quantities.

Rod photoreceptors maintain an electrical dark current. Ion pumping in that state consumes energy. Okawa and colleagues estimated more ATP consumption in mammalian rods in darkness than in bright light. This is a finding about rod cells, not total human-brain energy use. [1]

An fMRI comparison of eyes-open and eyes-closed conditions in darkness found different activity patterns, including visual and other sensory-system activity with eyes closed. Closing the eyes does not switch the visual system off. [2]

The useful explanation

Reducing competing visual input may make bodily sensations easier to attend to. That is the experiential rationale connecting darkness with Enhanced Biofeedback and Follow That Feeling.

Whether a particular setting reallocates measurable neural resources to interoception is a research question. The stronger “50% of brain power” explanation is unsupported and is not used as a fact. The practical preference for darkness does not depend on that percentage.

Research references

  1. Okawa H, Sampath AP, Laughlin SB, Fain GL. ATP consumption by mammalian rod photoreceptors in darkness and in light. Current Biology. 2008;18(24):1917–1921. DOI 10.1016/j.cub.2008.10.029.
  2. Marx E and colleagues. Eyes open and eyes closed as rest conditions: impact on brain activation patterns. NeuroImage. 2004;21(4):1818–1824. DOI 10.1016/j.neuroimage.2003.12.026.

Related review: Wong-Riley, Energy metabolism of the visual system, 2010. DOI 10.2147/EB.S9078. These references explain visual physiology; they are not trials of LDN or LS.