Uncovering the Role of Sleep in the Acquisition of Linguistic Knowledge

One remarkable aspect of human learning is our ability to build general knowledge from individual experiences. This general knowledge is central to virtually all cognitive functions, but is particularly important in language, as it allows us to use new words, phrases, and sentences that have not been communicated previously. For example, we understand the novel word 'untweetable' because we have general knowledge of the functions of affixes {un} and {able}. However, despite the significance of this form of knowledge for human communication, we know remarkably little about how it is acquired.

Recent research provides strong clues that sleep may play a vital role in the acquisition of general linguistic knowledge. In a previous ESRC project, we developed a laboratory analogue of language learning to track how general knowledge is built through multiple experiences with individual words. This research demonstrated that although new memories for individual items can be acquired rapidly, the process of discovering regularities across individual items to permit generalisation requires a period of overnight memory consolidation. The aim of the present research project is to discover whether sleep is the critical factor in the acquisition of general linguistic knowledge, and further, to describe the neural processes arising during sleep that facilitate this form of learning.

This proposal describes three work packages that combine methods at the leading edge of sleep science with our laboratory analogue of language learning to uncover how sleep impacts on the development of item-specific and general knowledge. In the first work package, we track the acquisition of item-specific and general knowledge when there is a delay between training and testing, and assess whether it matters if that delay consists of overnight sleep as opposed to daytime wake. In the second work package, we investigate how sleep deprivation before or after training impacts on the acquisition of item-specific and general linguistic knowledge. In the third work package, we use an olfactory cuing technique to reactivate memories of newly-learned information during sleep, and measure whether this reactivation enhances the acquisition of linguistic knowledge. We then take this experimental paradigm one step further to ask whether we can bias the course of long-term learning by selectively reactivating particular memories. In all experiments involving sleep, we use polysomnography to assess the importance of particular sleep stages or neural events during sleep for different forms of learning. We also assess learning in all experiments after one week to draw conclusions about the stability of new knowledge over the longer term.

International research has shown that the UK has one of the largest proportions of children who are sleep deprived, and that more than a quarter of the UK population gets on average less than five hours of sleep nightly. Given these statistics, it is of vital importance to understand what the consequences of poor sleep are for learning and memory. This research programme will address profound questions about how the brain continues to process new memories during sleep, how these sleep-related neural mechanisms shape the acquisition of long-term linguistic knowledge, and how sleep prepares the brain for new learning. Our findings will be transformative for theoretical models of learning, particularly as these apply to language, and will provide a range of new opportunities for creating substantive impacts within educational settings. We have developed a full programme of engagement with academic and non-academic stakeholders to realise this potential.

This project will deliver substantial new knowledge of the mechanisms that underpin human learning, in particular with respect to the role of sleep in this process. There is substantial interest in sleep and its influence on different forms of learning in a range of communities. However, we believe that our work will have the most rapid and powerful impact on users within educational communities. These include parents, students, teachers, lecturers, head teachers, educational psychologists, SENCOs, speech and language therapists, users involved with educational charities, and policy-makers.

There are two reasons why these user groups should be interested in our work.

First, there are growing concerns about the impact of poor sleep on student performance. Research has already linked poor sleep to changes in children's mood, cognition, and behaviour; and there is evidence that lack of sleep is associated with poorer school performance (although much of this work is based on correlation; see [1] for review]). Our research will make a vital contribution to this body of knowledge, because it will test experimentally in a highly-controlled manner how different sleep manipulations enhance or impair the acquisition of different types of knowledge. We believe that our experiments using sleep deprivation in particular could yield quite dramatic impacts on learning. In the short term, such an outcome would be influential in raising awareness of the importance of sleep, and motivating behaviour change (e.g. schools issuing evidence-based guidance to parents regarding the importance of proper sleep for learning). In the mid- to longer-term, we believe that our findings could contribute to ongoing policy discussions pertaining to the most appropriate time to begin the school day.

Second, our experiments will feed into an enhanced understanding of human learning generally, which could have impacts on teaching practice. Our interaction with professionals involved in education suggests a considerable desire to develop evidence-based teaching practices that enhance learning in student populations. Our research will be of interest to these communities because it will reveal not just whether sleep is important for human learning, but why. Though we would not expect for our findings to yield widespread changes in teaching practice, we will use this project to continue to build closer networks between educational professionals and researchers with expertise in the science of learning. In doing so, it is important to emphasise that the benefits of these connections are two-way. Just as educational professionals may value contact with experts in the science of learning, our research is enhanced by understanding challenges in the delivery of effective teaching and learning, and discovering opportunities in which new research could have a substantial impact on activity in the classroom.

Our experience of building bridges with these users through other ESRC projects has been highly positive and effective. In order to continue to build these bridges and deliver tangible impacts, we have carefully planned a strategy for engaging with these users. This strategy includes presentations in fora that attract these users, exploiting and enhancing our connections within this area, capitalising on our South East Research Network for Schools to invite relevant practitioners to workshops focused on learning, and continuing to raise awareness through media contacts and by writing general interest articles in outlets with wide reach.

[1] Willingham, D. (2012). Are sleepy students learning? American Educator, winter, 2012-2013 edition.