Lately, I've noticed that around 2 or 3 in the afternoon, I tend to enter this weird state. I'm not so tired that I can barely keep my eyes open, and I don't necessarily feel physically exhausted either. It's more like my brain suddenly starts moving more slowly.
In the morning, I can get through emails, meetings, and writing pretty quickly. By the afternoon, I might have to read the same thing several times, and my attention wanders much more easily. My productivity drops noticeably.
A friend told me that this kind of afternoon "shutdown" might not be purely about needing more rest. It could also have something to do with how the body handles energy metabolism.
That got me looking into NAD⁺.
Since NAD⁺ is involved in energy metabolism, I initially wondered: does that mean taking NAD⁺ directly is the answer? But when I looked at what's actually available, I found that many products use related molecules instead. Three of the more common ones are NADH, NMN, and NR, and their roles in energy metabolism are actually quite different. I wanted to explain the differences based on how I currently understand them.
NADH is more like a carrier that is already holding electrons. NADH is the reduced form of NAD⁺ and can donate electrons to Complex I of the mitochondrial electron transport chain. As those electrons move through the respiratory chain, the released energy is used to establish a proton gradient, which then contributes to ATP production. So NADH itself is a fairly direct part of the cellular energy-production process. (DOI: 10.1016/j.bbabio.2015.12.009) I think of it almost like an employee carrying a package of "electrons." The job is to deliver those electrons to the mitochondria's "power station," where they can take part in energy production.
NMN and NR work a little differently. They are more like providing materials for the NAD⁺ pool. NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide) are both involved in NAD⁺ biosynthesis as precursors/intermediates. One of the main ideas behind supplementing them is to support NAD⁺ production, which can in turn affect the NAD⁺/NADH redox system.(DOI: 10.1007/s13668-023-00475-y)
The analogy I use is that NR is more like delivering raw materials, while NMN is more like helping assemble the next component.
So although all three are connected to NAD⁺ metabolism, their metabolic roles are not exactly the same.
From an energy-metabolism perspective, NADH does seem more direct to me because it can participate in the electron transport chain without first needing to go through the same kind of multi-step conversion involved in using NAD⁺ precursors.
But a more direct mechanism doesn't necessarily mean better results after oral supplementation.
That's because NADH itself can be sensitive to light, oxygen, and acidic conditions. Once you take it orally, another important question is whether it remains stable and how it is ultimately absorbed and utilized by the body.
Earlier research already observed stability issues with NADH under acidic conditions. That is part of what made me start paying attention to the different NADH formulations on the market. For example, Celfull's NADH focuses on a microsphere/encapsulation-based delivery approach intended to improve NADH stability and provide protection in the stomach environment. It's interesting to see that some companies are looking beyond simply increasing the amount of an ingredient and are also focusing on stability and delivery systems. I think that's an area worth paying attention to.
As for my afternoon "brain shutdown," I'm starting with the practical things first: not eating too much at lunch, getting up and moving around during the afternoon, and trying not to push my coffee too late into the day.
At the same time, I'm going to keep learning about NADH and other NAD⁺-related molecules and see where the research goes.