A new analysis from Monash University suggests that intense thinking may only modestly raise the brain’s energy use—about 5%—rather than draining a vast reserve. For many, fatigue after study or work feels dramatic, but researchers say stress and emotional strain play a larger role than a hard limit on brain power.
The study, which reviews decades of brain-imaging data, found that resting and active mental states share similar energy demands. When solving a logic puzzle or memorizing vocabulary, energy rises only in targeted brain regions, while other areas quiet down to keep overall balance. In short, the brain’s energy budget remains largely stable during heavy cognitive tasks. Data from researchers in the field indicate that the notion of widespread, wholesale “fuel depletion” is unlikely.
For Thai readers—university students facing exams, office workers with demanding projects, and older adults managing memory changes—these findings matter. If mental tiredness stems more from stress than from brain energy exhaustion, wellbeing guidance in schools, workplaces, and homes may need realignment toward stress reduction and healthy habits.
The brain accounts for roughly 2% of body weight but uses about 20% of daily energy. That’s around 0.3 kilowatt hours per day, a figure that dwarfs a typical smartphone’s power draw. Most of this energy supports ongoing housekeeping: neurons maintain membrane potentials and prepare to fire, even during long stretches of screens and meetings.
Historically, people blamed fatigue after exams or long negotiations on sudden spikes in brain energy demand. The Monash-led synthesis shows only modest energy increases in specific networks during difficult thinking, never a global surge. As one neuroscientist noted, “Even tough thinking boosts energy modestly, and only in certain networks.” Thai scientists emphasize that fatigue is less about fuel and more about stress responses and emotional regulation.
What drives the sense of mental drain? Stress and arousal during high-stakes tasks trigger the body’s fight-or-flight response, releasing cortisol and other hormones. In Thailand’s competitive educational and work environments, this stress can feel exhausting, even if brain energy remains sufficient.
The research also highlights the brain’s efficiency: everyday tasks—from heartbeat control to sensory integration—cost about 17 watts, comparable to a dim light bulb. By contrast, supercomputers performing similar functions consume megawatts, underscoring human brain efficiency. Evolution wired our nervous systems to conserve energy, a trait still relevant in today’s energy-rich lives.
To measure brain energy use, scientists use PET scans and fMRI to track glucose and oxygen. The evidence shows local, not wholesale, energy changes during mental work. Fatigue is more plausibly a response to stress and the brain’s regulatory impulses to rest before costs outweigh benefits.
Age and metabolic health matter. As glucose metabolism slows with age, and insulin resistance rises in many older Thais, glucose delivery to memory and executive regions can be affected. This points to maintaining metabolic health through nutrition, exercise, and disease prevention as a strategy to preserve cognition in later life.
Thailand faces rising diabetes and metabolic syndrome rates. Public health experts advocate nationwide “brain fueling” campaigns emphasizing balanced nutrition and physical activity. The Monash findings support these efforts and also suggest prioritizing stress management in schools and workplaces as part of a holistic approach to brain health.
Education systems, often criticized for high-stress testing, may benefit from shifting away from anxiety-driven performance toward wellbeing. Mindfulness practices, better counseling, and balanced assessment strategies could reduce fatigue more effectively than simply adjusting study loads. Some Thai schools are already implementing wellness breaks and social-emotional learning, aligning with evolving science.
Thai society’s modern pressures—long work hours, heavy study loads, constant digital multitasking—can elevate stress levels. The Buddhist idea of santiphap—inner calm and balance—pairs well with science-backed strategies for rest and recovery. Practices like meditation, mindful eating, and respectful social interactions help regulate the stress response and ease mental exhaustion.
Looking ahead, researchers expect technology to deepen our understanding of brain function, but the core conclusion is unlikely to change: the brain remains energy-efficient and resilient. Rather than fearing an empty brain tank, Thais can focus on reducing stress, balancing work and rest, and cultivating inner calm.
Practical takeaways for Thailand:
- Prioritize regular physical activity and a whole-foods–based diet to support metabolic health.
- Promote open discussions about emotional wellbeing at work and in schools.
- Integrate mindfulness and relaxation techniques into daily routines.
- Recognize limits of willpower when stress is high, and build supportive environments.
By blending contemporary science with Thai cultural values, it’s possible to strengthen brain health and resilience for all ages.
As global research and local experience converge, the message is clear: feeling mentally tired doesn’t prove brain energy is exhausted. It signals the need to manage stress and rest effectively. Thailand can continue advancing a healthier, more productive society by addressing stress alongside nutrition and exercise.
In-text references to research come from collaborations and reviews in neuroscience communities. Data and practical implications stem from research conducted at Monash University, complemented by insights from leading Thai health and education researchers.