Neuroscience / Tiago Palmisano

What are the Biological Consequences of Staying Up All Night?

Author: Tiago Palmisano

Editor: Aishwarya Raja

“Sleep is a waste of time.” It’s an opinion that, as a college student, I’ve been forced to occasionally consider when it’s midnight and a looming pile of work clashes with the possibility of a good night’s rest. And unfortunately, sleep deprivation is not limited to the overloaded college student; many urbanites find that their busy schedules require them to burn the midnight oil, and maybe even the 4 AM oil. Sleep is easily ignored when it gets in the way of studying for a difficult test, going out with friends, or clocking in an extra shift at work. But consistent sleep loss carries some significant and often underestimated biological consequences.

To understand why sleep loss is damaging, it is necessary to know how the body regulates sleep cycles. The first way your body tells you to get to bed is through sleep-dependent homeostatic regulation. The mechanism is simple – when we are awake, our body releases a neurotransmitter called adenosine. The longer we are awake, the more adenosine piles up in our brain, and at a certain level this excess of adenosine causes decreased alertness and increased tiring. The second way is via our circadian rhythm, which is dependent on signals from the environment called zeitgebers, such as a lack of sunlight or cold temperature. When the hypothalamus in our brain senses a zeitgeber, it sends a signal to the pineal gland to release the neurotransmitter melatonin, which also decreases alertness and makes us sleepy.

Therefore, these two physiological systems make us tired at night, and when we have been awake for a long time. It makes sense, then, that at midnight after a long day we are extremely tired; homeostatic regulation and circadian rhythm are in full effect. Now I know what you’re going to say, “Of course I get tired at midnight, but I can just use coffee and Red Bull to increase my alertness and stay up with ease.”

The hippocampus helps decide if information is stored in the long term memory, and this process can be weakened by sleep loss. (Source: Wikimedia)

Using caffeine, the energizing component of coffee and energy drinks, to fight off sleepiness is certainly a common and efficient tactic. However, decreased alertness is not the only effect of sleep deprivation. Evidence suggests that losing sleep also impairs higher-level cognitive skills, such as forming memories. When we absorb new information, a part of the brain known as the hippocampus decides if the information is worth storing. If it is, then the information is stored in the long-term memory. Studies have demonstrated that even a single night of sleep deprivation impairs the neural circuitry in the hippocampus, and prevents it from properly committing information to the long-term memory. So when you stay up late cramming for that difficult test, your brain will be less able to retain details, and when you attempt to recall them the next day, you’ll be left searching.

Furthermore, certain skills such as reasoning and memory formation are not stimulated by caffeine. Coffee and Red Bull will make you more alert, but no matter how much caffeine you ingest, your ability to remember details will decrease if you neglect to sleep. Studies have consistently linked sleep loss to a lower average GPA. The consequences of sleep deprivation, though, cut much deeper than an underperforming memory. Research has indicated that disrupting homeostatic regulation and circadian rhythm (or messing with the balance of adenosine and melatonin) may significantly impair the immune system. As a result, long-term sleep deprivation increases the risk of heart disease, stroke, type-2 diabetes and even certain types of cancer. In fact, the World Health Organization lists overnight work as a probable carcinogen.

Messing with the body’s natural sleep cycles is extremely risky. Trying to exchange sleep for studying, socializing, or working is like walking on the edge of a cliff. The potential consequences are too damaging to ignore. But realistically, most people will not choose to ignore the responsibilities of a busy schedule. Therefore, it is critical to learn to balance your body’s physiology while finding enough time to be productive.

A relatively healthy method of getting through a period where a full night’s sleep isn’t an option is to combine occasional two-hour naps with caffeine. The short naps allow for a partial correction of the chemical imbalances associated with sleep loss, and the caffeine prevents the low levels of alertness that most people experience immediately after a nap. Furthermore, consistent exercise has been shown to increase sleep quality and prevent tiredness when the body is awake, allowing sleep to be more effective.

Two years of college have taught me that a healthy sleep cycle can’t be ignored. You depend on your body for nearly everything, and you should hold a responsible attitude towards sleep. So if you must trade in some rest for that busy schedule, make sure to use naps, caffeine, and exercise wisely. And if you can, try not to always burn the midnight oil. Sleep isn’t a waste of time.

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