It is 3.30pm and like clockwork, you need your coffee or chocolate fix. No, you are not starving or being dramatic. Termed 3:30-itis (or the afternoon slump), this craving – a need for a scheduled pick-me-up, is a phenomenon that most of us can all relate to, from the stressed student to the overworked employee. You reach out for that necessary nibble, that sip of caffeine needed to get you through the rest of the day. But what explains such behaviour and intention? Is this event psychological, or is there an underlying biological basis to it? It turns out that both factors contribute, and there isn’t a straightforward answer. Let’s address the biological aspect first.
Human beings are governed by biological rhythms – our sleep, mood, hunger and body temperature are circadian, meaning they complete their cycle in 24 hours. These cycles are in turn, governed by our internal biological clock that helps ensure the different rhythms are in sync with one another . For example, our body temperature goes down as our sleep cycle activates at dusk, but tempering with our body temperature (like sleeping in a hot room) will disrupt our ability to fall and stay asleep. Each rhythm influences the other, even though they have their own distinct cycles.
Back to 3:30-itis. A number of processes are transitioning on and around this time. Your body has most likely finished digesting lunch and is starting detoxification, so the thirst you feel is, in essence, your body’s way of prompting you to take in more fluids to aid this process. Our body temperature also peaks in the late afternoon, so this combination of digestion, detoxification and cooling the body usually results in some feeling of lethargy. This is why most people distract themselves with coffee or a snack to perk up. Notice that the 3 pm coffee or snack seems just a little more rewarding than your mid-morning one? Interestingly, structures in our brain reward center (e.g. putamen) are circadian as well. Its activity dips in the late afternoon, so when a “reward” (e.g. coffee) is presented, it can appear more pleasurable due to its unexpected timing .
For the psychological aspect, it is no coincidence that we crave comforting (but oh-so-delightfully- sinful) foods during this period. Stress either suppresses hunger cues or self-control, resulting in us craving different types of foods when bored, stressed or depressed. Food involves a complex mix of evolutionary, social and emotional factors, so it is related to comfort, bonding and often enjoyed upon meeting significant milestones . For example, when women are lacking magnesium from blood loss during menstruation, they don’t crave spinach but chocolate, though both are rich magnesium sources. , in essence, is largely due our history of being pacified with candy as kids, as well as societal associations of chocolate with pleasure. Hence, although a quick run could effectively wake us up more than a latte during the afternoon slump, we convince ourselves that we “deserve” the latter to last through the day. Think about this the next time you reach for that candy bar when snacking at work.
Still, it is fortunate that such impulses and desires can to some extent, be controlled. Some research suggests that food cravings can be curbed with cognitive tasks within the same modality. This means if you constantly have vivid images of coffee, performing a visual task would reduce cravings. Given that most of our food cravings tend to be driven by vision rather than taste, smell, touch or audition, consider keeping a game of Tetris handy the next time 3pm rolls around .