By Pesach Benson • March 19, 2026
Jerusalem, 19 March, 2026 (TPS-IL) — Why do people chase a good meal, fall in love, or keep scrolling late into the night? For decades, scientists have said it’s because these things feel good. But a new study suggests something far more practical may be driving our behavior: not pleasure, but the brain’s constant effort to manage the body’s energy.
A new Israeli study is challenging one of neuroscience’s most familiar ideas — that the brain’s reward system exists to make us feel pleasure.
Instead, scientists from the Hebrew University of Jerusalem say the system may serve a more practical purpose: helping the body manage its energy.
The study, led by Matan Cohen and Professor Shir Atzil, suggests that chemicals like dopamine and opioids are not primarily “feel-good” signals. Rather, they help the body decide when to spend energy and when to conserve it.
“We have long been told a simple story about reward,” the authors wrote, referring to the common idea that dopamine drives desire while opioids create pleasure. “But this pleasure-centric view has a major flaw — it doesn’t explain why these same chemicals are active during stress, pain, or even immune responses.”
The researchers argue that the brain is constantly managing what they call an energy budget. Every action — thinking, moving, even keeping the heart beating — requires energy, and using it efficiently can be critical for survival.
Under this model, dopamine acts like a “go” signal, preparing the body to respond to challenges by increasing alertness and mobilizing resources. Opioids act as a “slow down” signal, helping the body return to a stable, energy-saving state once the challenge has passed.
“Reward is a measurable biological mechanism aimed at optimizing energy management,” Atzil said. “This is a basic evolutionary principle that unites physiological regulation, learning, and behavior.”
The study also reframes motivation. Instead of acting because something feels good, people may act because the body senses a need that requires energy to resolve.
When the body faces a challenge — such as stress or changes in blood sugar — it must respond, which costs energy. The researchers describe this as “effort.” When the problem is resolved and the body can return to balance, it saves energy. That saving, or “gain,” is what the brain treats as a reward.
Over time, the brain learns to repeat actions that reduce energy costs and avoid those that waste energy, shaping behavior around efficiency rather than pleasure.
“Instead of viewing dopamine and opioids as signals of pleasure, we propose that they function as components of a physiological regulatory system that optimizes energy expenditure over time,” Cohen said.
This framework may also explain why these chemicals are involved in systems such as digestion, breathing, and immune responses, suggesting they play a broader role in maintaining balance across the body.
It could even reshape how scientists understand complex experiences like music, relationships, and social bonding, which may reflect learned behaviors that improve the body’s efficiency over time.
If the brain’s reward system is really about managing energy rather than producing pleasure, it could reshape how doctors approach mental health and addiction. Conditions such as depression, addiction, obesity, and diabetes may be better understood as disruptions in how the brain regulates the body’s energy, not simply imbalances in mood or reward. That could shift treatment toward stabilizing underlying systems — including metabolism, stress hormones, sleep, and inflammation — alongside traditional psychiatric care.
In addiction, the model suggests that drugs and compulsive behaviors may serve as short-term ways to manage physiological stress or energy deficits. Future therapies could focus less on suppressing cravings and more on addressing the biological needs those behaviors are trying to meet.
The findings also point to practical changes in everyday health and behavior. Habits like sleep, diet, exercise, and stress management may directly shape motivation and decision-making by influencing the body’s energy balance. Designing environments and routines that lower “friction” — for example, simplifying healthy choices or building consistent schedules — could make long-term behavior change easier to sustain.
The study was published in the peer-reviewed Neuroscience & Biobehavioral Reviews.
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