It happens to the best of us: 2:00 p.m. rolls around and our energy dips. Often, we attribute it to a post-lunch sugar crash. Or maybe, because there are only a few hours left in the workday, we feel less motivated to complete tasks. But new research poses another theory about why we’re lacking in gusto later in the day.
The study, published in the Journal of Neuroscience, found that among healthy young men, varying energy levels at different points during the day are tied to changes in the brain’s reward system — a unit of neurotransmitters, chiefly, dopamine, that influences motivation, desire and pleasure.
Using neuroimaging technology, Swinburne University PhD candidate Jamie Byrne and her supervisor Professor Greg Murray compared the “activation” of the brain’s reward system in 16 young men, whom they had participate in gambling activities at 10 a.m., 2 p.m. and 7 p.m. They found that at 2 p.m., the activity in the left putamen, a key area in the brain’s reward center, was the lowest.
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The reasoning? According to Byrne and Murray, because the expectation for rewards is lowest in the morning and evening, we’re more likely to exert energy during those times. Perhaps that’s because there’s less pressure for achievement, so we feel we have less to lose? Or, as David DiSalvo explains in Forbes, “if you don’t expect something is coming, you expend more energy to get it.”
"This is important, because it shows the brain's reward system is probably connected to the internal clock that primes 24-hour physiological and psychological processes," Byrne told the Daily Mail. The researchers noted that this could have implications for treating depression, substance abuse issues, sleep disturbances and other disorders which see a fluctuation of symptoms at different times throughout the day.
Beyond getting a good night's sleep, exercising regularly, try eating these healthy snacks during the workday to help stabilize your energy and mood.