Does sleeping reduce biases?

Have you ever taken the implicit bias test? If you have not, I recommend you do so. This test is interesting, in that is measures your implicit biases – the ones you don’t know exist. But first, a caveat: you may learn things about yourself that are surprising. For example, even if you do not feel that you prefer one race over another or one gender over another, this test may suggest otherwise. Here’s how it works: you see a series of photos and words that represent categories. You are then asked to select, as quickly and accurately as possible, which one of the categories the presented picture belongs to. So if you are shown pictures of traditionally European faces and traditionally Asian faces, you would be prompted to select which category they belong to (Asian/American or European/Foreign). During the next round, you are asked to select which faces belong to different categories (European/American or Asian/Foreign). See the difference? Your reaction time for categorizing these faces is compared between sessions, and you are then told whether you are biased to link European or Asian faces with your country (assuming you are an American). There are multiple tests, and most of them will tell you that you are indeed biased in some way. Most of us don’t want to be biased, so what do we do about it? A new study involving sleep, unexpectedly, has a suggestion.

Things learned during the day are processed in the brain during sleep. Memories are formed during deep stages of sleep, and connections are strengthened. Recently, researchers have found a way to ‘hack’ the sleeping brain. This hack begins when the research participant is awake. When they are learning something, a unique tone is played non-invasively in the background. The learned information forms a neural connection with this tone, such that replay of the tone will reactivate the learned information. Here’s where it gets good – replaying the tone during sleep can reactivate the memory and then, since sleep is an ideal time for memory formation, the memory is strengthened. Using this method, researchers can selectively choose which information they want to solidify in the brain.

So, what does this have to do with implicit biases? A recent investigation took a group of white participants and tested their racial and gender biases. They found, not surprisingly, that they had a bias toward members of their own race and they also had a bias that linked women with “the arts” and men with “the sciences.” They then trained these participants to associate black individuals with better associations and also women with the sciences. By practicing these associations, their biases were reduced, gauged using the same test. In the meantime, unique tones were being played that were associated with these non-biased associations.

Next, the participants all went to sleep. Only half of the participants, however, had the same tone played for them during their deepest stage of sleep (the stage that is very important for memory formation). Half of the participants had the gender bias tone replayed, and half had the racial bias tone replayed.

After awakening, biases were again tested. Only those that had tones replayed during the night woke up without biases. The ones who did not have the tones played woke up to have biases similar to the ones they had before they had practiced the non-biased associations. Amazingly, these differences in groups lasted even after 7 days had passed. The reduction in biases was effective for both gender and race.

So what does this all mean? It means, simply by having people practice some non-biased associations and then by reactivating these associations during the night using benign tones, the researchers were able to reduce sexism and racism in this group of white participants. Admittedly, this memory-reactivation-during-sleep task is farfetched and it would be difficult to apply on a broader scale, but it’s a start.

What does any of this have to do with sleep apnea? Not much, except for the fact that sleep apnea disrupts sleep. When sleep is disrupted, processes such as the one described above (without the sound cues) are disrupted as well. If you value the formation of new memories, keep your sleep strong by having your sleep apnea treated and sticking to your treatment. Sleep is important – and hacking sleep may be something that we see more often!

Source: Hu, X., Antony, J. W., Creery, J. D., Vargas, I. M., Bodenhausen, G. V., & Paller, K. A. (2015). Unlearning implicit social biases during sleep. Science, 348(6238), 1013-1015.

Janna Mantua


Janna is a PhD Student / Graduate Research Assistant at University of Massachusetts Amherst with a background in clinical sleep research and psychology. Janna Mantua is a PhD student in the Behavioral Neuroscience department at the University of Massachusetts. Her research focuses on sleep and aging, with specific projects on cognitive health, inflammation, memory formation, and neuroimaging. Prior to her PhD work, Janna was involved in research on sleep apnea and cognitive decline at the NYU Sleep Disorders Center.

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