Sleep May Solve Grammar Gremlins

Beinecke Library

Do you know when to use who versus whom? Affect versus effect? If you’re stumped, first crack open your textbook, but then make sure to get a good night’s sleep – it could help! According to newly published research, sleep plays an important part in learning grammar, and perhaps other complex rules as well.

In their study the researchers used an invented grammar to develop sets of letter sequences. They also assessed each sequence for its “associative chunk strength,” or memorable letter clusters. Sequences with lots of these “chunks” could be easy to memorize, which the authors differentiate from learning, or rule acquisition. Participants were then shown these sequences and asked to recreate them from memory. They were not told that the letter sequences were constructed according to a set of grammatical rules.

The participants then waited 15 minutes, 12 hours, or 24 hours before being tested to see whether they had retained or learned the rules. Participants in the 12 hour group that started in the evening and those in the 24 hour group slept between experimental phases. When the testing began, participants were told that grammatical rules were in use and asked to judge whether letter sequences were grammatical.

Participants that slept between stages, i.e. those in the 12 hour and 24 hour groups, performed significantly better than those who did not sleep prior to the test. Specifically, those who slept between tests were better able to discern grammatical from not-grammatical letter sequences. The same was true for letter sequences with fewer chunks of memorable letter clusters. Their results also indicate that the length of the waiting period, whether it was 15 minutes or hours, did not significantly affect the participants’ performance.

Students, the next time you think you can forgo a good night’s sleep, think again! Sleep may just help you learn those tricky grammatical rules.

Citation: Nieuwenhuis ILC, Folia V, Forkstam C, Jensen O, Petersson KM (2013) Sleep Promotes the Extraction of Grammatical Rules. PLoS ONE 8(6): e65046. doi:10.1371/journal.pone.0065046

Image: Childrens talk, English & Latin by Beinecke Library.

Could sleepless nights of terror be good for you?

Lying awake and listening for demonic footsteps after Paranormal Activity 4 may turn out to be more helpful to your mental health than trying to fall asleep. A study published earlier this month in PLOS ONE shows that losing sleep can prevent frightening memories from taking hold in the brain, at least in rats.

A good night’s sleep has many advantages, including improving our ability to recollect facts or learned motor skills. Losing sleep impairs these kinds of memory, but the impact of sleep deprivation on other kinds of memory, such as that of traumatic events, is still poorly understood.

In this study the authors Tankesh Kumar and Sushil Jha, found that when rats were trained to develop a conditioned fear response to a sound they heard, this response was twice as strong in rats that slept for six hours after the training than in those that stayed awake for this period of time. According to the authors, this result suggests that the rats that stayed awake hadn’t learned to be afraid of the sound as well as the better-rested animals had.

Despite the ill effects of sleep deprivation and associated poor memory under other circumstances, the authors suggest that losing sleep after a traumatic event can actually help prevent fearful memories from taking hold in the brain, potentially providing long-term benefits like reducing the risk of post-traumatic stress disorder (PTSD) or anxiety disorders.

Related PLOS ONE research published last year studied the effects of a similar, odor-induced fear conditioning exercise in rats, and observed changes in brain activity during sleep following the exercise. The researchers also found that these changes correlated with the strength of the fear response observed in rats the next day.

If that scary movie is still keeping you awake, read more PLOS ONE research about how dolphins can go 15 days sleeping with only half of their brain, how ostriches sleep like platypus, or the sleep behavior of the most mysterious creature of them all, the human teenager.


Citations: Kumar T, Jha SK (2012) Sleep Deprivation Impairs Consolidation of Cued Fear Memory in Rats. PLoS ONE 7(10): e47042. doi:10.1371/journal.pone.0047042

Barnes DC, Chapuis J, Chaudhury D, Wilson DA (2011) Odor Fear Conditioning Modifies Piriform Cortex Local Field Potentials Both during Conditioning and during Post-Conditioning Sleep. PLoS ONE 6(3): e18130. doi:10.1371/journal.pone.0018130

Image: another rat by asplosh on Flickr, CC-by license