Are you taking Thomas Piketty's Capital on holiday with you? Do you do sudoku for the promised brain workout it provides? Have you forced yourself to sit through improving documentaries when you would rather have been watching MasterChef? Bad news: it may all be for nothing.
According to experts, everything from our gadgets to our eating habits and ultimately modern life itself are eroding our brains, chipping away at neural pathways and making us slower, denser and less capable of original thought.
Most recently, a study by the University of Montreal, published this month, found that eating large quantities of saturated fat can have a significant effect on brain function, damaging the neural circuits that govern motivation and even leading to a sort of addiction.
Since the 1930s IQs across the world have largely increased thanks to better living conditions, improved nutrition and education. But scientists are now raising concerns that for the last decade, IQ scores have not just been levelling out but declining, and our collective intelligence has dropped by one IQ point in the last 50 years.
As well as learning new things you need to protect the home front, it seems. So, if you want to salvage what damp tissue you have left, here are some of the surprising ways you could be ruining your brain.
1 Tucking into a full English breakfast
Consuming large amounts of soggy saturated fats (bacon, buttery toast and fried eggs) hamper the brain's dopamine function, a vital neurotransmitter responsible for motivation. Studies show that fatty diets impair cognitive flexibility, slow reaction times, damage memory and bring on feelings of depression in rats and other animals. The University of Montreal study found that high-fat feeding can cause "impairments in the functioning of the brain circuitry profoundly implicated in mood disorders, drug addiction, and overeating".
2 Juggling too many balls at once
Earl Miller, an expert on divided attention and a neuroscientist at Massachusetts Institute of Technology says: "The brain is not wired to multitask. When people think they're multitasking, they're actually just switching from one task to another very rapidly, and every time they do, there's a cognitive cost." It means we use up glucose (brain fuel) faster, exhausting and discombobulating our minds more quickly. "Multitasking prevents deep, creative thought as we switch back and forth, backtracking, constantly starting from scratch each time. As a result, thoughts are less new and more superficial," says Miller. Just spotting an email mid-task is enough to reduce your IQ by 10 points as your mind wanders from the job. Juggling multiple balls floods the brain with cortisol (the stress hormone) and adrenalin (the fight or flight hormone), which also prevents clear thought.
3 Just Googling it
Having unlimited information available 24/7 at the jab of a button, both at home and on the move, is both a blessing and a neurological curse. Being able to Google addresses, phone numbers, recipes, names, events, even what your friends have been up to recently, means we no longer rely on memory. The brain's hippocampus deals with processing new memories. While Googling doesn't necessarily affect it per se, it does affect the technique we use to store memories inside it. For example, research by Columbia University showed we are now more likely to recall where we save information rather than the information itself, and Microsoft says our attention spans have suffered, falling from an average of 12 seconds 15 years ago to eight now.
4 Those reality TV binges
We may not yet have conclusive proof but our long-held suspicion that reality TV is rotting our brains may well be correct. An Austrian study by psychologist Markus Appel showed 81 participants a fake reality-like screenplay based around what a football hooligan got up to during a day, then asked them to take a general knowledge test. Those who had seen the reality show beforehand fared worse then those who had not. Appel blamed media priming - the idea that what we watch, see and listen to influences our behaviour - and claimed it extended to cognitive performance, too. In short, you are what you watch. "What you've been thinking about recently or seeing recently [is] at a higher level in your consciousness, so your brain is predisposed in that direction," is how another psychologist, Joanne Cantor, put it.
5 Having your fruit and eating it
A 2012 UCLA study on rats showed that too much fructose - a simple sugar found in fruits, honey and vegetables - effectively slowed the brain by affecting insulin's ability to help brain cells convert sugar into energy for thought. But eating omega-3 fatty acids (flaxseed oil, mackerel, herring and trout) counteracted this mental disruption by protecting against damage to the synapses, the chemical pathways in the brain. Dr Sarah Brewer, a medical nutritionist, warns of the damage sweet things can do to your grey matter: "Brain cells need glucose to function but too much in a short time will cause a sugar rush and make you feel over-wired."
6 Jet lag and other night-time disruptions
We all know jet lag makes you foggy-headed for a day or so after landing, but in fact its dulling effects can last for weeks. Studies on hamsters found that regular disruption to our internal circadian rhythm - our day-night pattern - halved the normal rate of new neuron birth in the hippocampus and the effects were still noticeable a month after the last "disruption". The hamsters' learning ability plummeted too. Professor Lance Kriegsfeld from the University of California at Berkeley said of the findings: "What this reveals is that, whether you are a flight attendant, medical resident, or rotating shift worker, repeated disruption of circadian rhythms is likely going to have a long-term impact on your cognitive behaviour and function."
7 Walking and chewing gum
Not too long ago, we thought chewing gum was a good thing, neurologically speaking. Neuroscientist Earl Miller said: "Chewing your gum is a physical exercise that increases the flow of blood to the brain, boosting cognitive function by giving it extra energy."
But a recent experiment poured cold water on the theory: the act of chewing distracted participants from short memory tasks such as learning the order of items on a list.
Dr Sarah Brewer says: "When people chew gum for hours, it may cause a problem with distraction. As soon as the flavour, goes I'd recommend taking it out."