Napping or Light Exercise.. An American Doctor Determines Which is More Beneficial for Memory

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It is difficult to deprive oneself of sleep, focus, and absorb new information. For those who work at night or face intermittent periods of severe sleep deprivation, getting enough rest may not always be available, according to what was published by CNN News Network.

A recent study published in the Proceedings of the National Academy of Sciences compared two strategies for protecting memory after sleep deprivation, specifically aerobic exercise and napping. The researchers wanted to know if short bouts of exercise actually provide some of the same cognitive benefits that napping does. As it turns out, the answer may be yes.

To help people understand how to apply these findings, Dr. Leana Wen, a health expert and assistant clinical professor at George Washington University, told CNN: The study included a limited number of healthy adults aged 18 to 35, who were kept awake for 30 hours.

The 54 participants were then randomly assigned to three groups. One group engaged in cycling for 20 minutes at a moderate to high intensity, at 80% of their maximum heart rate. Meanwhile, another group was given the opportunity to take a 90-minute nap. The control group sat on a stationary bike for 20 minutes without exercising.

The participants then viewed 150 images while researchers recorded their brain activity using EEG. They were unaware of a subsequent memory test. After three days, having had the opportunity to recover from sleep deprivation, they were shown the original images mixed with new ones and asked about the images they remembered.

Participants who exercised correctly recognized 56% of the images, compared to 57% among those who took a nap and 46% in the control group. Both the exercise group and the nap group performed significantly better than the control group, with memory performance increasing by nearly 21% after exercise and by 23% after napping. No statistically significant difference was observed in the benefit between exercise and napping.

Interestingly, participants who took a nap reported feeling much less tired afterward, while those who exercised reported levels of fatigue similar to the control group. Despite feeling equally tired, the exercise group significantly outperformed the control group in the memory test.

Dr. Wynn added that sleep deprivation hinders the brain's ability to encode new information. After prolonged wakefulness, sleep pressure accumulates, and the neural processes necessary for forming memories become less efficient.

EEG recordings indicate that exercise helped mitigate some of these effects. It reduced the neural stress index in brain areas responsible for memory tasks. One possible hypothesis is that exercise helps the sleep-deprived brain use its available cognitive resources more efficiently.

The 20-minute exercise falls under a broader concept known as "light exercise," although it was longer than most. These are short bursts of physical activity, typically lasting between 30 seconds and five or ten minutes. Activities include climbing stairs, brisk walking, squats, or other activities that elevate the heart rate. Studies have indicated that these small doses of movement have health benefits, such as improving cardiovascular fitness and even reducing the risk of cancer and dementia.

Dr. Wynn stated that one of the most interesting findings was that exercise and napping achieved similar benefits in improving memory performance, but through different neural processes.

Napping altered the baseline state of the fatigued brain due to lack of sleep. Individuals in the napping group felt less tired, and their electroencephalogram (EEG) indicators of sleep pressure decreased, which is the biological drive for sleep that increases the longer one stays awake. Measures related to this improved brain state were closely associated with the participants' ability to form new memories. Exercise did not alleviate sleep pressure in the same way. Instead, it seemed to enhance memory processing efficiency. The difference can be understood as follows: napping gives the brain some of the sleep it needs, while exercise helps the brain work more effectively despite ongoing sleep deprivation.

Dr. Wynn clarified that precision is required regarding what was tested; this was a small laboratory study involving young, healthy adults who remained awake continuously for 30 hours in laboratory conditions. The researchers tested one specific exercise regimen and one aspect of cognition. Therefore, it is still unknown whether the same benefit would be realized in cases of chronic sleep restriction or among older adults with medical conditions or when engaging in different types or levels of exercise.

The study also did not show that exercise restores attention levels, reaction speed, judgment ability, or other numerous functions negatively affected by sleep deprivation. These issues are subjects for broader studies conducted in real-world conditions, especially among shift workers and others who regularly suffer from sleep deficiency.