Nicotinamide mononucleotide, often shortened to NMN, has drawn significant research attention in recent years because it feeds into the production of NAD+, a molecule that cells rely on for energy and repair. One protein that depends heavily on NAD+ is called Sirtuin 1, or SIRT1. Animal and human studies have pointed to SIRT1 as a possible player in how the brain manages sleep and biological clocks. That connection raised a natural question: could raising NAD+ levels through NMN supplementation improve the way people sleep?
A study published in Scientific Reports by Sakai Noriaki and colleagues set out to answer exactly that. The researchers used a mouse model that lacked SIRT1 specifically in the brain, then layered on NMN supplementation to see what happened to sleep and circadian behavior. The results were more nuanced than many might expect, and they carry useful context for anyone following the NMN or NAD+ literature.
The role of SIRT1 in sleep biology
SIRT1 is a protein sometimes described as a cellular energy sensor. It becomes more active when NAD+ levels are high, which tends to happen during periods of fasting, exercise, or caloric restriction. Because NAD+ levels decline with age, and because SIRT1 activity tracks with NAD+, researchers have theorized that both molecules may influence age-related changes in sleep quality.
Earlier work had suggested that SIRT1 plays some role in regulating circadian rhythms, which are the roughly 24-hour biological cycles that govern when we feel alert or sleepy. However, the field lacked a detailed picture of what happens to sleep when SIRT1 is removed specifically from brain tissue, as opposed to the whole body. This study was designed to fill that gap.
How the study was structured
The research team created mice that were genetically modified to lack SIRT1 only in the brain, called brain-specific knockout mice, or BKO mice. These animals were compared against normal littermate mice of the same genetic background, referred to as wild-type mice.
The scientists recorded detailed sleep data, measuring how much time each group spent in different sleep states: non-REM sleep, REM sleep, and wakefulness. They also tracked how the animals recovered after sleep deprivation, which is a standard way to test whether sleep pressure builds and resolves normally. Circadian period lengths were measured separately to see whether the biological clock itself was affected by losing brain SIRT1.
For the NMN portion of the study, middle-aged mice from both groups received NMN in two different ways. One group received it by injection into the abdomen for ten days, representing an acute short-term protocol. Another group received NMN orally for two months, representing a chronic long-term protocol. Sleep was then recorded and compared to each animal's own baseline.
What the knockout mice revealed
When the researchers compared BKO mice to wild-type mice, they found something that initially seems counterintuitive. Removing SIRT1 from the brain did not meaningfully change overall sleep architecture. The total amount of time spent in each vigilance state, meaning wakefulness, non-REM sleep, and REM sleep, was similar between the two groups. Sleep homeostasis, which refers to the body's drive to recover lost sleep, also looked comparable.
The researchers concluded from this that brain SIRT1 likely plays only a minor functional role in basic sleep-wake regulation. That is a meaningful finding because it suggests the connection between SIRT1 and sleep, while real, may operate through pathways that are either redundant or located outside the brain.
There was one notable difference. BKO mice showed reduced delta power during non-REM sleep. Delta power is a measure of slow brain waves during deep sleep, and lower delta power is generally associated with lighter or less restorative non-REM sleep. This confirmed a pattern that earlier research had hinted at, and it suggests that brain SIRT1 does influence the quality or depth of sleep even if it does not change how much sleep occurs.
What NMN supplementation did and did not do
The NMN results were perhaps the most headline-worthy part of the study. Neither the ten-day injection protocol nor the two-month oral protocol produced measurable changes in sleep duration or sleep quality compared to control conditions. This was true in both normal wild-type mice and in the SIRT1 knockout mice.
The researchers were transparent about this null result. They noted that it represents what they describe as the first preclinical evidence directly testing whether NMN supplementation improves sleep. The absence of a direct sleep effect does not mean NMN has no value in the broader metabolic context, but it does mean researchers should be cautious about assuming that NMN will translate into better sleep simply because it raises NAD+ levels and supports SIRT1 activity.
The study authors offered a possible reconciliation with reports from human studies where NMN has been associated with improvements in fatigue and sleep quality. They suggested that any sleep-related benefits observed in people may be indirect. NMN may improve muscle function and energy metabolism, and those improvements could then reduce fatigue and make sleep feel better, rather than NMN acting directly on the brain circuits that control sleep.
Limitations and what comes next
Animal studies always carry the caveat that mouse biology does not map perfectly onto human biology. Sleep in mice follows different timing patterns than sleep in humans, and the doses and delivery methods used in animal research do not always reflect how humans consume supplements.
The study also focused specifically on middle-aged mice, which was a deliberate choice to model the population most likely to seek sleep-related interventions. Whether younger or older animals would respond differently to NMN remains an open question.
The delta power finding is worth following in future research. If brain SIRT1 influences the depth rather than the amount of sleep, then interventions that target SIRT1 activity may someday be studied for their effects on sleep quality metrics rather than sleep duration. Whether NMN can shift those metrics through chronic systemic exposure, or whether more targeted approaches would be needed, is something the literature has not yet resolved.
Context for NAD-related research
This study adds an important data point to a growing body of literature on NAD+ precursors and aging. The broader research landscape includes work on NAD+ itself, its various precursors, and the downstream proteins like SIRT1 that depend on it. The fact that a two-month oral NMN protocol did not move sleep metrics in a controlled animal study is the kind of rigorous negative finding that helps researchers narrow down where and how these molecules actually act.
For readers who follow the research on compounds like NMN and its relatives, the takeaway is that the mechanisms connecting NAD+ metabolism to sleep are likely more indirect and more complex than early enthusiasm suggested. The study does not close the door on this line of inquiry. Instead, it redirects attention toward metabolic and muscular pathways as the more plausible routes through which NAD+ precursors might eventually affect how people feel when they wake up.
