Written by the Nuvirox Research Team
Key Points
- Moving into management doesn't add more hours of work — it adds a different kind of work: constant, low-stakes-seeming decisions that add up.
- A well-known replication effort found little evidence for "willpower as a depletable tank," which suggests the exhaustion is more about accumulated context-switching and sleep loss than a used-up resource.
- New managers also tend to lose sleep at both ends — earlier starts, later catch-up work — and that sleep debt compounds day over day.
Short answer: yes, and the research on stress and decision-making backs up why. Individual contributors solve problems. Managers solve other people's problems, on other people's timelines, all day, often with incomplete information. That's a structurally different cognitive load, and it shows up as exhaustion even on days that look, on a calendar, pretty ordinary.
What actually changes when you move into management?
The honest answer is: almost everything about how your day is structured. As an individual contributor, you typically control the order of your own tasks. As a new manager, your day is largely built out of other people's interruptions — a direct report's question, a peer's escalation, a scheduling conflict that needs a ruling right now. Each of those is a small decision. None of them individually feels hard. But you're making dozens of them, out of order, with your own "real work" squeezed into the gaps.
This is a textbook description of what stress researchers call a repeated, low-grade stressor pattern, rather than one big acute event. Chronic stress research on the hypothalamic-pituitary-adrenal (HPA) axis has found that the body's cortisol response is especially sensitive to the timing and novelty of a stressor — activity tends to run higher right at the onset of a new, unfamiliar demand, and gradually settles as the situation becomes familiar.
Is "decision fatigue" during the day a real, measurable thing?
This is where it gets more nuanced than most productivity articles let on. The popular idea of decision fatigue leans on "ego depletion" — the theory that self-control draws down a limited mental resource, like a battery. It's an intuitive, appealing idea. It's also one of the more contested findings in psychology.
A large, pre-registered, multi-lab replication attempt — 23 labs, over 2,100 participants, all running the same standardized protocol — found an effect size close to zero for classic ego-depletion tasks, essentially failing to replicate the original effect. That doesn't mean your end-of-day fog is imaginary. It means the mechanism is probably not a literal depletable "willpower tank." A more likely explanation, supported by separate sleep research, is that new managers are simultaneously juggling more context switches and losing more sleep — and it's the sleep debt and switching cost doing the damage, not a used-up resource.
What the research actually shows
Miller, Chen & Zhou (2007), a meta-analysis of HPA-axis studies: Cortisol activity is shaped heavily by how new and uncontrollable a stressor feels, with hormonal output typically elevated at the start of a stressful period and settling as the person adapts. This maps onto the common experience of a rough first several months in a management role that gradually eases. Miller GE, Chen E, Zhou ES. If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans. Psychol Bull. 2007;133(1):25-45. PMID: 17201569.
Van Dongen et al. (2003), a controlled sleep-restriction study: Restricting sleep to 6 hours a night for two weeks produced cumulative cognitive impairment comparable to one or two full nights of total sleep deprivation, and participants often didn't perceive how impaired they'd become. New managers frequently report exactly this pattern — trimming sleep on both ends to keep up — and the research suggests they may be underestimating the cost. Van Dongen HPA, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep. 2003;26(2):117-126. DOI: 10.1093/sleep/26.2.117.
Honest counterweight — Hagger et al. (2016), the ego-depletion registered replication: The specific mechanism people usually blame (a depletable willpower reservoir) did not hold up in a large, pre-registered replication. This matters because it means the fix probably isn't "build more willpower" — it's addressing the sleep debt and interruption load directly. Hagger MS, Chatzisarantis NLD, et al. A multilab preregistered replication of the ego-depletion effect. Perspect Psychol Sci. 2016;11(4):546-573. PMID: 27474142.
What this exhaustion won't tell you
None of this research diagnoses burnout, anxiety, or depression, and a rough transition period is not the same as a mental health condition. If the exhaustion doesn't meaningfully ease after several months, or comes with persistent low mood, dread, or trouble functioning outside work, that's worth raising with a doctor rather than treating as a normal management growing pain.
How long does this typically last?
There's no single validated timeline for "new manager adjustment," but the stress-adaptation research above is consistent with a pattern where the sharpest exhaustion clusters in the first few months, as novelty and unfamiliarity are the biggest drivers of elevated stress reactivity. Most people report the load feeling more manageable once routines, delegation habits, and trust with the team are established — typically somewhere in the three-to-six-month range, though this varies widely by role and team size.
Frequently asked questions
Is it normal to feel more tired as a manager than I did as an individual contributor, even though I'm doing “less” hands-on work?
Yes — this is one of the most commonly reported experiences in the management-transition literature. The shift from focused, self-directed work to constant, other-directed interruptions is a different cognitive load, not a lighter one.
Does taking more breaks actually help with this kind of fatigue?
Short breaks that protect sleep and reduce back-to-back meeting load tend to help more than the popular “willpower recovery” framing would suggest, since the research points to sleep debt and switching costs as bigger drivers than a depleted mental resource.
When should I actually be concerned about how tired I feel as a new manager?
If exhaustion persists well past the first few months, worsens instead of easing, or comes with anxiety, low mood, or trouble sleeping even when you have the chance to sleep, that pattern is worth discussing with a doctor rather than waiting it out.
Does experience eventually make this easier?
Most people report it does, largely because familiarity reduces the “new and uncontrollable” quality of the stressor that the HPA-axis research identifies as a key driver of elevated stress reactivity.
FROM NUVIROX
Why we formulated NAD+ Restore
We built NAD+ Restore around the two most-researched approaches to supporting cellular energy production, for people whose days are long on decisions and short on recovery time. It's formulated to be taken consistently, and it's backed by a 60-day money-back guarantee — long enough to actually judge whether it fits into your routine.
Learn more about NAD+ Restore →The bottom line
The exhaustion that comes with a new management role is well documented, even if the popular explanation (a depleted willpower tank) doesn't hold up as well as people assume. The more supported story is a combination of unfamiliar, uncontrollable demands and quietly accumulating sleep debt. If the daily grind of context-switching sounds familiar, you might also relate to why constant task-switching is so mentally draining, or to the specific flavor of self-doubt covered in why imposter syndrome is so exhausting. For a look at how this compares to another form of decision-heavy volunteer or unpaid leadership work, see why serving on a nonprofit board is so draining. And if you're wondering why exam-style, high-stakes decision periods hit so hard too, the research on licensing exam exhaustion covers similar ground.
References
- Miller GE, Chen E, Zhou ES. If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans. Psychol Bull. 2007;133(1):25-45. PMID: 17201569.
- Van Dongen HPA, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep. 2003;26(2):117-126. DOI: 10.1093/sleep/26.2.117.
- Hagger MS, Chatzisarantis NLD, et al. A multilab preregistered replication of the ego-depletion effect. Perspect Psychol Sci. 2016;11(4):546-573. PMID: 27474142.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.