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Katie Lewis Lewis

Dr Katie Lewis Lewis

Sir Henry Wellcome Postdoctoral Research Fellow

School of Medicine

+44 29206 88381
Hadyn Ellis Building, Room 2.28, Maindy Road, Cardiff, CF24 4HQ
Available for postgraduate supervision



I am currently a Sir Henry Wellcome Postdoctoral Research Fellow. My research investigates the link between sleep and mental health, and aims to answer questions like: "Why do sleep problems affect mood in some people more than others?" and "Can we use information on sleep to predict if or when someone will become unwell?" I use longitudinal and genetic data on sleep and mood to answer these questions, including data from smartphone apps and activity monitors.















Lewis, C., Lewis, K.J.S., Roberts, A., Edwards, B., Evison, C., John, A., Meudell, A., Parry, P., Pearce, H., Richards, N., Jones, I., Bisson, J.I. (2022). Trauma exposure and co-occurring ICD-11 post-traumatic stress disorder and complex post-traumatic stress disorder in adults with lived experience of psychiatric disorder. Acta Psychiatrica Scandanivica, DOI: 10.1111/acps.13467. Epub ahead of print.

Martin, J., Wray, M., Agha, S.S., Lewis, K.J.S ., Anney, R., O'Donovan, M., Thapar, A., Langley, K. (2022) Investigating direct and indirect genetic effects in attention deficit hyperactivity disorder (ADHD) using parent-offspring trios. Biological Psychiatry, DOI: 10.1016/j.biopsych.2022.06.008. Epub ahead of print.

Lewis C., Lewis K., Roberts A., Evison C., Edwards B., John A., Lloyd K., Pearce H., Poole R., Richards N., Robinson C., Jones I., Bisson J.I. (2022). COVID-19-related posttraumatic stress disorder in adults with lived experience of psychiatric disorder. Depress Anxiety. doi: 10.1002/da.23262.   Epub ahead of print.

Oakes D.J., Pearce H.A., Roberts C., Gehrman P.G., Lewis C., Jones I.*, Lewis K.J.S*. (2022). Associations between comorbid anxiety and sleep disturbance in people with bipolar disorder: Findings from actigraphy and subjective sleep measures. Journal of Affective Disorders, Apr 12:S0165-0327(22)00404-9. doi: 10.1016/j.jad.2022.04.065. Epub ahead of print.

Lewis, K.J.S., Gordon-Smith, K., Saunders, K.E.A., Dolman, C., South, M., Geddes, J., Craddock, N., Di Florio, A. Jones, I., Jones, L. (2022) Mental health prior to and during the COVID-19 pandemic in individuals with bipolar disorder: Insights from prospective longitudinal data. Bipolar Disorders, 00:1–9. doi:10.1111/bdi.13204.

Lewis, K.J.S., Lewis, C., Roberts, A., Richards, N., Evison, C., Pearce, H., Lloyd, K., Meudell, A., Edwards, B.M., Robinson, C.A., Poole, R., John, A., Bisson, J., Jones, I. (2022). The effect of the COVID-19 pandemic on mental health in individuals with pre-existing mental illness. BJPsych Open, 8(2), E59. doi:10.1192/bjo.2022.25

Lewis, K.J.S., Tilling, K., Gordon-Smith, K., Saunders, K.E.A., Di Florio, A. Jones, L., Jones, I., O'Donovan, M.C., Heron, J. (2022). The Dynamic Interplay Between Sleep and Mood: An Intensive Longitudinal Study of Individuals with Bipolar Disorder. Psychological Medicine, 1-10.   DOI: 10.1017/S0033291721005377

Lewis, K.J.S.*, Martin, J.*, Gregory, A.M., Anney, R., Thapar, A., Langley, K. (*joint first author). Sleep disturbances in ADHD: Investigating the contribution of polygenic risk for ADHD and sleep-related phenotypes. (2022). European Child & Adolescent Psychiatry. DOI: 10.1007/s00787-021-01931-2

Lewis, K.J.S ., & Gregory, A.M. Heritability of Sleep and its Disorders in Childhood and Adolescence. (2021). Current Sleep Medicine Reports , 7, 155-166. DOI: 10.1007/s40675-021-00216-z

Gordon-Smith, K., Lewis, K.J.S ., Vallejo Auñón, F.M, Di Florio, A., Perry, A., Craddock, N., Jones, I., Jones, L. (2020). Patterns and clinical correlates of lifetime alcohol consumption in women and men with bipolar disorder: Findings from the UK Bipolar Disorder Research Network. Bipolar Disorders, 22(7),731-738. DOI: 10.1111/bdi.12905

Lewis, C., Lewis, K.J.S., Kitchiner, N., Isaac, S., Jones, I.,Bisson , J.I . Sleep disturbance in post-traumatic stress disorder (PTSD): a systematic review and meta-analysis of actigraphy studies. (2020). European Journal of Psychotraumatology, Jul 9;11(1):1767349.

Lewis, K.J.S., Richards, A., Karlsson, R., Leonenko, G., Jones, S., Jones, H.J., Gordon-Smith, K., Forty, L., Jones, L., Escott-Price, V., et al. Comparison of Genetic Liability for Sleep Traits Among Individuals With Bipolar Disorder I or II and Control Participants. (2020). JAMA Psychiatry, 77(3):303-310. DOI: 10.1001/jamapsychiatry.2019.4079

Lewis, K.J.S., Di Florio, A., Forty, L., Gordon-Smith, K., Craddock, N., Jones, L., & Jones, I. (2018). Mania triggered by sleep loss and risk of postpartum psychosis in women with bipolar disorder. Journal of Affective Disorders , 225, 624-629.

Lewis, K.J.S., Gordon-Smith, K., Forty, L., Di Florio, A., Craddock, N., Jones, L., & Jones, I. (2017). Sleep loss as a trigger of mood episodes in bipolar disorder: individual differences based on diagnostic subtype and gender. British Journal of Psychiatry, 211(3), 169-174.

Barber, S. & Swaden Lewis, K. Antimicrobial Resistance. House of Commons Library Briefing Paper CBP 8141, 15 November 2017.

Lewis, J., Bisson, S., Swaden Lewis, K ., Reyes-Galindo, L., Baldwin, A. (2017). Cardiff sciSCREEN: A model for using film screenings to engage publics in university research. Research for All, 1(1), 106-120.

Dent, C.L., Humby T., Lewis, K ., Plagge, A., Fischer-Colbrie, R., Wilkins, J.F., Wilkinson, L.S., Isles, A.R. (2016). Impulsive choices in mice lacking imprinted Nesp55. Genes, Brain & Behaviour, 15(8), 693-701.

Lewis, K.J.S., Foster, R.G., & Jones, I. R. (2016). Does sleep and circadian rhythm disruption trigger postpartum psychosis? British Journal of Psychiatry. 208(5), 409-11.

Lewis, K., Elam, K., Sellers, R., Rhoades K., Bevan Jones, R., Thapar, A., Rice, F., Collishaw, S., Harold, G., & Thapar, A. (2013). The Depression Impairment Scale for Parents (DISP): a new scale for the measurement of impairment in depressed parents. Psychiatry Research , 210, 1184-90.

Lewis, K.J.S., Mars, B., Lewis, G., Rice, F., Sellers, R., Thapar, A.K., Craddock, N., Collishaw, S., & Thapar, A. (2012). Do parents know best? Parent-reported vs. child-reported depression symptoms as predictors of future child mood disorder in a high-risk sample. Journal of Affective Disorders , 141, 233–6.

Lewis, K.J.S., Borst, G., & Kosslyn, S.M. (2011). Integrating visual mental images and visual percepts: new evidence for depictive representations. Psychological Research , 75, 259-71.

Public Engagement:

I have a keen interest in public engagement and I am passionate about widening access to science. I have worked with a number of groups including: Public Health Wales Healthy Schools Scheme, Step Up Summer School for Widening Access to Higher Education, Gwent Police, Wales Gene Park and Cardiff Scouts.

Other talks and science communication:


£30,488 – Wellcome Trust Research Enrichment - Public Engagement Award (01 January 2023 – 30 September 2025).

£300,000 – Wellcome Trust Sir Henry Wellcome Postdoctoral Fellowship "Using genetics, neurophysiology and longitudinal data to disentangle the complex relationship between sleep and mood disorders" (01 October 2021 – 30 September 2025).

£44,945 – Wellcome Trust (Institutional Strategic Support Fund Consolidator Award) "Do sleepless nights lead to manic days? Using online mood monitoring and genetics to decipher the role of sleep in bipolar disorder." (29 April 2019 – 01 May 2020).


BSc Psychology with Year-Long Work Placement  - University of Bath (2010)

PhD Medicine, Division of Psychological Medicine & Clinical Neurosciences - Cardiff University (2018)

Honours and awards

  • Health and Care Research Wales Rising Research Star Award (2022)
  • Judges' Prize and People's Choice Prize for presentation at Division for Psychological Medicine and Clinical Neurosciences Annual Research Day (2018)
  • 2nd Prize – Poster Award, Spotlight on Social Sciences Conference (2014)
  • 1st Prize – Poster Award, Cardiff and Vale Research Conference (2013)
  • University of Bath Psychology Award for Highest-Graded Dissertation (2010)

Committees and reviewing


  • Chair, Maintaining Women in Science (MWIS)


  • Journal of Adolescence
  • Frontiers in Psychiatry (Review Editor)
  • Biological Psychiatry
  • British Journal of Psychiatry
  • Journal of Affective Disorders
  • Journal of Child Psychology and Psychiatry 


GW4 BioMed2 2023/24 Studentship

Application Deadline: Wednesday, 2nd November 2022 ***

Bipolar disorder (BD) is a mood disorder where people experience disabling episodes of both high and low mood. Originally, it was thought that people with BD experience discrete mood episodes surrounded by periods of wellness, but new evidence suggests this is an oversimplification. In fact, people with BD continue to experience abnormal mood regulation even during periods when they would be considered "well". Compared to healthy controls, people with BD experience heightened responses to emotional stimuli and more rapid changes in mood states. This project aims to answer the question: what can dynamic features of mood tell us about clinical outcomes and long-term prognosis of BD? Prior BD research suggests those with worse mood regulation have a more severe and impairing course of illness and may be more likely to have particular subtypes of BD. However, these studies often have small sample sizes because participants need to record their mood at frequent intervals over long periods of time. This prospective data collection is not traditionally done in psychiatry (which often relies on cross-sectional assessment) but may be more clinically useful.

Technological advances now make it easier than ever to collect vast amounts of data in large samples. This presents new challenges: how do we address the increased chance of missing data? How do we combine thousands of datapoints from multiple people when most statistical methods used in psychiatry allow ≤10 timepoints per person? How do we account for seasonal changes in mood? Dynamic features of mood can be defined in multiple ways (e.g. the intensity of peaks and troughs in mood over time, the amount of time taken to recover from mood disturbances), but which are most useful for aiding our understanding of BD? New statistical methods which draw on other fields such as engineering and economics can address these issues whilst also opening exciting new avenues for how we examine and conceptualise mood dynamics.

This PhD project offers a unique opportunity to be at the frontiers of mood dynamics research. The student will learn cutting-edge statistical methods for analysing data from digital technology and apply them to data from the Bipolar Disorder Research Network (BDRN) – the largest individual cohort of people with BD in the world. Over 1200 BDRN participants have completed online weekly mood questionnaires ( for an average of 2 years, resulting in ≥100,000 datapoints. This dataset represents a powerful resource to examine mood dynamics in real-world settings and link this with the rich clinical, demographic and biological data in BDRN.


A1) Derive traditional and novel measures of mood dynamics in people with BD. The student will draw on resources from several disciplines (psychology, engineering, economics), including cutting-edge statistical methods for analysing time series data (dynamic structural equation modelling).

A2) Test which mood dynamics are most useful for predicting course of illness and clinical characteristics of BD. The student will test associations between mood dynamics measures identified in A1 with the rich clinical and demographic data available in BDRN (e.g. age of onset, BD subtype, number of mood episodes, personality traits, presence of other psychiatric co-morbidities).

A3) Test the hypothesis that greater mood instability indicates a greater genetic susceptibility to BD. The student will test whether mood dynamics are predicted by genetic risk for BD and related disorders (e.g. major depressive disorder, schizophrenia).

There will be several opportunities for the student to take ownership and steer the project. For A1 and A2, they will identify research gaps through a review of mood dynamics literature and by collaborating with people with lived experience of BD. In A3, they will be able to decide which polygenic risk scores to include in addition to those for BD (e.g. neuroticism).

More information, including application guidance

The GW4 BioMed2 MRC DTP studentship will include:

  • Full tuition fees at the UK/Home rate
  • Stipend at the minimum UKRI rate
  • Research & Training Support Grant (RTSG) of £2,000 per year
  • £300 annual travel and conference grant based on a 4 year, full-time studentship.

Part-time study is also available and these funding arrangements will be adjusted pro-rata for part-time studentships. Throughout the duration of the studentship, there will be opportunities to apply to the Flexible Funding Supplement for additional support to engage in high-cost training opportunities.