We all know caffeine for its benefits as a pick-me-up, providing us with a burst of energy and alertness, whether it’s the force that gets you out of bed in the morning, or the fuel that helps you finish that last-minute essay at 3am. Some of us might know it as something that makes us feel unwell, on edge or shaky, giving us with an adrenaline rush that we really didn’t want before an already nerve-racking day or when we were actually hoping for an early night. Particularly to the latter group, caffeine as a stress-reducer might seem a little counter-intuitive. Caffeine has the effect of increasing our heart rate, and stimulating our central nervous system, making us more alert and awake, or even anxious. This doesn’t sound particularly like something which can have a calming effect, and reduce stress, but recent studies have shown that caffeine may actually be able to reduce stress, and have even pointed out some biological reasons that this might happen.
Amongst its many other effects, caffeine blocks receptors in the brain for a chemical called adenosine. Adenosine is a hormone which usually inhibits the release of several neurotransmitters, including dopamine, adrenaline, acetylcholine and serotonin. When adenosine receptors are blocked, its effectiveness is decreased, so levels of these chemicals, dopamine, adrenaline, acetylcholine and serotonin increase. This increased adrenaline helps to explain some of the effects of caffeine, like increased alertness and energy, as adrenaline is a hormone involved in making us feel “pumped up”, and increases our heart rate to prepare us for activity. This is also a factor in the anxiety some people feel after taking caffeine: their “fight or flight” response goes into overdrive, making them feel on-edge, twitchy and anxious, as their body begins to act as if responding to a threat.
Recent research has found that blocking these same adenosine receptors can also reduce the effects of chronic stress (note: chronic stress is a response to stress over a prolonged period of time, for example, many months or even years, while acute stress is a response to individual and less common stressful events and is actually thought to be good for you). Since caffeine has this effect, it is possible that caffeine may in fact reduce chronic stress, as many frequent coffee-drinkers might testify.
However, this does not necessarily make caffeine a suitable drug to treat disorders which can be caused by chronic stress, like anxiety or depression, as you might think from reading this. These receptors, while they are connected to chronic stress, might not be the actual cause of stress. Additionally, the multiple side effects of caffeine would make this a strange choice of drug. People who suffer from anxiety often avoid caffeine, as it increases their levels of adrenaline even more on top of the increased adrenaline of anxiety itself, and rather than helping them to feel less stressed, they instead find their condition is worsened by drinks containing caffeine, such as coffee or energy drinks. Caffeine’s other side effects are also very similar to the symptoms of anxiety, including nausea, shaking, fast heartbeat, tremors, irritability, and even anxiety itself is listed as a side effect of caffeine.
Caffeine is the most widely used drug in the world, but this doesn’t mean it has the same effects on everyone, and regular coffee-drinkers can become tolerant to its effects, or even addicted to the substance. Coffee, the most frequent way in which caffeine is consumed, can lead to increased blood pressure, weight gain and can even increase the chance of heart disease in individuals with a specific genetic mutation. However, it’s not all bad, with some studies suggesting it could have antidepressant effects, and is linked to “cleaner” arteries. The increased alertness that comes with that first cup of coffee in the day can increase our ability to pay attention, which comes in handy for those early starts, particularly when a task demands the level of attention that most people simply can’t muster up early in the morning. It might not be a magical cure-all for stress, but it does have its positive effects, and maybe there’s more to be discovered about exactly how it can reduce chronic stress and depression.