Can't Take A Nap? This 20-Minute Habit May Help Your Brain Instead

Twenty to forty percent of adults worldwide aren't getting enough sleep1. And while most of us know how different we feel after a bad night, the effects go beyond being a little more tired or reaching for an extra coffee.

Sleep plays a major role in our ability to form new memories. When we don't get enough of it, the brain becomes worse at taking in new information and storing it for later, which can affect everything from learning something at work to remembering a conversation or making a decision based on past experience.

Of course, the best solution to sleep deprivation is more sleep. But that's not always an option, especially for shift workers, healthcare professionals, new parents, frequent travelers, or anyone coming off a particularly rough night.

So researchers wanted to know: When catching up on sleep isn't immediately possible, is there anything we can do to help protect the brain in the meantime?

Researchers compared a nap, exercise, & doing nothing after sleep loss

For the new study1, published in Proceedings of the National Academy of Sciences, researchers brought healthy young adults into a lab and kept them awake for 30 continuous hours. They then randomly assigned participants to one of three groups: 20 minutes of aerobic exercise, a 90-minute nap, or 20 minutes with no intervention.

Afterward, participants looked at a series of images without knowing they'd later be tested on them. Three days later, once they'd had time to recover from the sleep deprivation, researchers showed them a mix of old and new images and measured how well they remembered what they'd previously seen. Throughout the experiment, researchers also used EEG to track brain activity during memory formation.

This allowed them to look beyond whether exercise or sleep helped and ask a more interesting question: How was each intervention helping the sleep-deprived brain?

Both exercise & a nap helped protect memory

Both interventions worked surprisingly well. Participants who exercised or napped had, on average, 22% better memory performance than those who did neither.

But their brains seemed to get there in very different ways.

After the nap, memory performance was more strongly related to measures of the brain's overall state before participants saw the images, including markers related to sleep pressure and neural fatigue. Researchers think the nap may have helped reset the brain into a state that was simply more receptive to learning new information.

Exercise appeared to work differently. In that group, only brain signals directly involved in encoding memories significantly predicted how well participants remembered the images. Rather than reducing sleep pressure in the way a nap might, exercise seemed to help the tired brain use the resources it still had more efficiently.

Researchers describe this as "neural degeneracy," which sounds more negative than it is. It essentially means the brain can use different pathways to arrive at a similar outcome. Here, resting and moving produced comparable benefits for memory through two distinct mechanisms.

The takeaway

The most practical part of this study is that it gives us another option on days when we're underslept.

If you have the time and opportunity, a longer nap may help reduce some of the sleep pressure that's accumulated in the brain. But a 90-minute nap isn't exactly realistic in the middle of most workdays. A 20-minute bout of aerobic exercise, on the other hand, may be much easier to fit in and could offer another way to support memory when you're running on too little sleep. 

That doesn't mean you should start swapping sleep for workouts. This study looked at acute, lab-induced sleep deprivation in healthy young adults, not the chronic short sleep many people experience in everyday life. 

But we all have nights when enough sleep simply doesn't happen. This research suggests that on those days, moving your body or finding time for a real nap may help your brain function a little better until you can get the sleep you actually need.