{
  "abstract": "Introduction Sleep duration is regulated by day length in seasonal animals and in humans living in pre-industrial societies, presumably an evolutionary adaptation to optimise survival in the dark months of the year. Global studies of data from consumer sleep devices have suggested that human sleep duration is shorter during long photoperiods at both hemispheres, with no difference at the Equator. However other studies report none, or minimal variation in sleep duration across the seasons in modern humans, and no study has adequately controlled for confounding lifestyle factors. In this study we leverage the extensive demographic and lifestyle data available in UK Biobank to investigate seasonal variation in sleep.Methods Inclusion was restricted to participants who reported having no chronic disease at the time of recruitment. Sleep duration was the self-reported number of hours sleep in every 24 hours and insomnia was self-reported sleep problems. A harmonic regression model with sine and cosine terms corresponding to a 12-month period was fitted to assess seasonal variation. Potential confounders included as covariables were age; sex; ethnicity; Townsend area-deprivation score, physical activity and sedentary behaviour; alcohol intake and smoking status; chronotype; work schedule and location of the UK Biobank assessment centre.Results Sleep was seasonally patterned with slightly increased sleep duration and more frequent reports of symptoms of insomnia in the winter months ( figure 1).Discussion In agreement with data from consumer wearables, we report seasonal patterns of sleep duration in the participants of UK Biobank independent of multiple demographic and lifestyle-related covariables. This suggests that humans may have innate patterns of winter dormancy and summer activity in common with other animals that evolved at northern latitudes. Further work to elucidate the sensitivity of human sleep patterns to annual changes in day length are warranted.Abstract P63 Figure 1Seasonal variation in sleep duration (A) and in the probability of reporting symptoms of insomnia in UK Biobank participants",
  "authors": [
    {
      "affiliations": [
        "Maynooth University, Maynooth, Ireland"
      ],
      "name": "Cathy Wyse"
    },
    {
      "affiliations": [
        "University of Edinburgh, Edinburgh, UK"
      ],
      "name": "Amber Roguski"
    },
    {
      "affiliations": [
        "University of Edinburgh, Edinburgh, UK"
      ],
      "name": "Daniel Smith"
    },
    {
      "affiliations": [
        "Maynooth University, Maynooth, Ireland",
        "Future Neuro Research Centre, Maynooth, Ireland"
      ],
      "name": "Lorna Lopez"
    }
  ],
  "title": "P63 Seasonal variation in sleep duration and symptoms of insomnia in 294,868 UK Biobank participants",
  "uid": "7b7ff116-d2c1-5886-b6d6-97e655a9d53d"
}