Sitting at a desk, reading a textbook may feel like one of the least physical activities you can undertake, but the results of your studying depend on numerous biological factors, including your body clock. Learning and intellectual performance are firmly tied to the body’s internal time.
Planet Earth’s rotation – once every 24 hours – is deeply ingrained into human physiology, and each internal process, from digestion to muscle strength, waxes and wanes on a cycle called a circadian rhythm. A master clock in the brain maintains these rhythms and stays attuned to the time outside using morning daylight.
Learning is a physical process that involves strengthening certain connections among the brain’s neurons. That ability to change the brain varies according to the time of day; in particular, it’s enhanced during the day and more difficult at night. So how can you use the time to your advantage?
Ride the wave
Every day, your body temperature starts low and rises slowly until late in the evening, when the wave crests and plunges down again for the night. Your internal temperature only varies by about a third of a degree, but that’s enough to change the way your body – and, in particular, your brain – works. With more heat comes faster chemical reactions.
Thinking is a series of chemical exchanges, so calculation speed, memory formation and accuracy increase as the day goes on and peak with body temperature and heart rate – usually in the late afternoon. During the night and early hours of the morning, even if you’re not sleep deprived, those powers decline.
Know your avian type
Being a morning lark or a night owl is not a choice – you’re born with it. Each of us has a chronotype, a tendency to get up early or stay up late, or perhaps flit somewhere in the middle. As much as you might force yourself into another schedule, your chronotype is largely genetic, and it’s affected by the length of your circadian cycle. A longer cycle leads to a later chronotype.
Age also plays a large role in a person’s chronotype. While young children are early birds, adolescents begin to shift into a later phase. In the late teens and early 20s, we are the latest sleepers – and latest wakers – that we will ever be. After this peak comes a shift back to morningness. In fact, researchers proposed that whereas the end of puberty is defined as the time when your bones stop growing, the end of adolescence is the abrupt biological shift away from late sleeping that occurs around the age of 20.
Being a night owl means hitting your cognitive peak later in the day. Unfortunately, it also comes with real problems for students. Research shows that morning-active students have higher academic achievement and feel more immersed and focused in their studies, whereas night owls struggle with fatigue in the classroom. This problem disproportionately affects men and extroverts, who are each more likely to be night owls. Not only is extroversion linked to evening chronotypes, it also tends to exacerbate the evening-active lifestyle because that’s when much of our social activity goes on.
Study at a fixed time
One of the most powerful factors that influenced the evolution of human memory was the need to anticipate regular events – such as the appearance of food or predators – in the environment. Consequently, memory is closely linked to the internal clock, and when we learn things, there is an internal time stamp attached to those memories.
The brain can prepare for a bout of intensive focus if it’s required at the same time every day. A fixed-time learning session leads to better cognitive performance at that time of day, and if it the task is demanding enough, your study sessions can even reset your body clock.
Keep a sleeping schedule
Decide on a bedtime and a time for waking up, then stick to it. Even on weekends, daily routines should remain roughly the same. Staying up much later on the weekend and sleeping in on Sunday – as many people do – leads to social jet lag. If you normally go to bed at 10.30pm, but on Friday and Saturday you stay out until 1.30am, it’s as if you have flown from your home in New York to Los Angeles for the weekend. Attention problems tend to follow during the week, even with a full eight hours of sleep every single night.
Nap before you’re tired
No matter how good your time-management skills, sometimes assignments pile up and deadlines converge, particularly towards the end of the term. Few students get through their academic careers without pulling some late nights. A common approach is to power through the exhaustion at night, then nap the next day to recover. But naps are actually better at preventing fatigue than at helping you to recover from it. Napping during the day before a late night will boost your work and learning performance, even if you don’t perceive the difference in yourself.
Take a morning walk before you learn
Within the first half hour after waking, a flood of stress hormones – called the cortisol awakening response – surges through the body. This deluge catapults us out of the grogginess of sleep inertia and helps energize us for the day ahead, but it also impairs the formation of long-term memories (pdf). Anything that’s important to remember should be saved for the second hour after waking.
Another obstacle to memory formation is the sleep hormone melatonin. A few minutes outside in the morning daylight will clear the melatonin out of the bloodstream and lend your brain the clarity it needs to start learning.