Mathematical model of light and circadian data improves sleep timing in people with schizophrenia

The typical rhythms of activity, sleep, and light exposure. (a), (d): Light (yellow trace), activity (gray trace), 6-sulphatoxymelatonin (aMT6s) acrophase (red circles) and sleep timing (horizontal gray bars). (b) and e): Average light exposure over the 24-hour period. The shaded regions from white through to dark gray indicate the fraction of time spent at different light levels (>500 lux; between 500 and 100 lux; between 100 and 10 lux,

The likelihood of disturbed sleep timing in schizophrenia patients is higher than that of intrinsic biological factors.

Application of a physiologically-based mathematical model to light exposure, sleep timing data and biological markers of the circadian clock, has revealed that disturbed sleep timing in people living with schizophrenia is more likely to be related to light exposure than to intrinsic biological factors. Surprisingly the combination of digital health data and the mathematical model suggested that normalization can be achieved by increasing light availability. It does not require the imposition and/or sitting in front light boxes, as recommended in current brightlight intervention therapies.

It is well-known, that poor sleep is caused by people suffering from mental health conditions. Poor sleep is often associated to distress, poor mental health, and poorer quality life. In agreement with previous studies, the current reanalysis and analysis of data from earlier published data showed that people with schizophrenia spend more time sleeping in bed, wake up later, sleep in an irregular pattern, and are more likely to be in bed. Some participants drifted asleep during the 24-hour day, especially in winter.

Whether altered sleep timing patterns are related to changes in biologically-determined characteristics of the body clock that drives sleep timing, or to behaviourally determined patterns of light exposure which normally synchronize the clock to the 24-hour day, is an active topic of debate.

The multidisciplinary team of a mathematician, circadian and sleep physiologists and a psychiatrist at the University of Surrey, the University of Umeå (Sweden) and King’s College London respectively joined forces to address this issue. A mathematical model was created that feeds the unique data and includes biological factors that influence sleep timing and how environmental factors affect the body clock.

While light is an important aspect of life, it has been acknowledged that current interventions require people to be able to see light boxes that emit bright light at specific times of day. These interventions suggest that schizophrenia sufferers must be forced to wake up on a specific schedule to receive maximum benefit. Mathematical analyses show that this is not necessary. It is much easier to modify the light availability pattern. The mathematical principles that regulate sleep timing by light will also be implemented.

This approach can be tailored to individual needs and can be implemented with the help of digital health technology. These interventions could be co-designed by patients to make them more manageable. Light interventions can be more effective at addressing sleep disturbances by increasing adherence and tuning them to individual needs.

The authors present a method for implementing their approach in their paper. This could be used as a model for data-model fusion techniques to reduce sleep disturbance in a variety of disorders such as schizophrenia, bipolar disorders and delayed sleep phase syndrome. The current focus of the Surrey researchers is dementia. This is due to funding from the UK Dementia Research institute.

Professor Anne Skeldon, University of Surrey’sDepartment of Mathematical, said:

“Our clinical framework suggests a cost effective way to help people sleep more frequently through ‘light availability” interventions that are co-designed and tailored to individuals’ daily lives. Light interventions can be tailored to individual preferences and physiological characteristics with the help of clinicians.

Professor Derk Jan Dijk, Surrey Sleep Research Centre stated:

“Combining digital healthcare technology to collect data and mathematical models for the effects light has on circadian rhythms is a powerful way to develop personalized interventions.”

Associate Professor Katharina Wulff from Umeå University in Sweden said:

“With these technologies at our disposal, the response of the strong seasonal daylight variations up here in Sweden’s Northern part could potentially be tracked by individuals. Then, mathematical modeling could be used to produce personalized light regimes if supplementary light is required.

While LED face masks are very popular on social media, they can disrupt your sleep.

More information:
Anne C Skeldon et. al., Extracting Circadian Parameters and Sleep Parameters in Longitudinal Data from Schizophrenia for Design of Pragmatic Lighting Interventions Schizophrenia Bulletin (2021). DOI: 10.1093/schbul/sbab124

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University of Surrey

A mathematical model of light and circadian data improves the timing of sleep in schizophrenia patients (2021, December 2)
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