Sulbutiamine has been used to treat asthenia, a condition of low energy and lethargy usually reported by convelescing patients. There is some evidence that it does work and numerous patents regarding this material.
Sulbutiamine is described as a centrally acting cholinergic agent like donepezil which is used for Parkinson's and Alzheimer symptoms. These drugs inhibit the destruction of acetylcholine (a stimulating neurotransmittor) in the brain. Increased concentrations of acetylcholine are believed to be responsible for greater alertness, memory and acuity.
Sulbutiamine is an ACE inhibitor, which results in greater brain acetylcholine concentrations which would increase concentration, memory, alertness, etc.
From Drugs Today:
"Sulbutiamine, a highly lipophilic thiamine derivative, is the only antiasthenic compound known to cross the blood-brain barrier and to be selectively active on specific brain structures directly involved in asthenia."
Because I believe a good night sleep is so important, I like the idea of supporting the diurnal, or circadian rhythms. "This study demonstrated the clear action of Sulbutiamine upon the mechanisms regulating waking and light sleep."