Rest to Remember

How a workout or a siesta could help protect your memory from sleep deprivation

Photo by Kate Stone Matheson on Unsplash

Sleep deprivation is arguably the world’s most universally relatable problem. From teenagers to college students to overworked professionals, nearly all of humanity struggles to achieve the medically recommended 8 hours of shut-eye due to various personal and professional obligations. While often unavoidable, this is bad news for our brains. Scientists aren’t sure of the exact mechanisms, but they agree that sleep is essential for our brains to process and consolidate our memories.

To quote Dr Robert Stickgold, renowned sleep researcher from Harvard Medical School, “During sleep, your brain is taking your memories, reactivating and looking at them again, and storing them in a more efficient and effective form.”

Crucially, as Dr Stickgold mentions, it is only during slumber that our brains can process all of the information that we have absorbed during the day and integrate it with the knowledge we already have. This is what helps us to learn better and acquire new skills, but insufficient sleep can hamper this vital system.

Despite our best efforts, it simply isn’t feasible for many of us to sleep as long as we need to. How then can we keep our brains healthy and stave off the cognitive risks associated with prolonged sleep deprivation?

A possible solution has emerged from a paper published recently in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). A team of researchers has discovered that two of the cheapest, most common, most widely accessible practices — exercising and napping — might help to counteract the negative effects of sleep loss on memory performance. Specifically, they examined a type of memory called episodic memory.

As the name suggests, episodic memory is the reason why you can remember details about personal events, the times and places in which they occurred, and the emotions they evoked in you. All of these components characterise the various episodes in the series that is your life. The ability to accurately recall the past is crucial for making sound decisions about the future, and, unfortunately, is sensitive to sleep deprivation. According to the study’s authors, just one night of sleep loss can impede the brain’s ability to encode episodic memories.

The study participants comprised 54 healthy individuals aged 18 to 35. To begin with, the research team had the participants undergo 30 continuous hours without sleep. They then divided the participants into three groups — one group was subjected to 20 minutes of aerobic exercise, the second was made to nap for 90 minutes, while the third group received neither treatment.

Following these treatments, the participants were shown a series of images. After three days, they were shown a mixture of old and new images and had to report whether each image was novel or had been encountered earlier. During these events, the researchers used electroencephalography (EEG) to measure electrical activity in the participants’ brains.

On average, both the nap and exercise groups displayed 22% higher memory performance than the third group. Interestingly, there was no significant difference in memory performance between the nap and exercise groups, suggesting that napping and exercising are roughly equally effective at countering sleep deprivation-induced memory impairment.

The EEG results revealed that the exercise and nap groups had less delta wave activity in their brains compared to the third group. Delta waves make up a specific pattern of electrical activity in the brain that is associated with deep sleep.

By observing specific brain responses triggered by sleep deprivation, the researchers discovered that exercising and naps are each associated with slightly different processes in the brain. Exercise assists with efficient neural processing, while napping makes the brain more receptive to new information.

While these results are promising, the authors emphasise that these measures are no substitutes for a proper night’s rest. The findings are likely to prove most beneficial to professionals in critical industries such as healthcare and transportation, where workers are required to maintain their mental faculties despite being forced to contend with regular sleep deprivation. The authors believe that accessible, inexpensive measures such as napping and light-to-moderate exercise can help professionals who are unable to follow recommended sleep hygiene practices.