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Abstract Background Social jetlag is a chronic disruption of sleep timing that is characterized by different sleep timing during workdays and free days. Social jetlag has been associated with disturbed glucose metabolism, insulin resistance, and increased risk of metabolic syndrome and type 2 diabetes. In this study, we aim to investigate whether a combination of bright light therapy in the morning, bright light reduction in the evening and sleep advance instructions for 3 weeks reduces social jetlag and if this results in improvement of glycemic and metabolic control, sleep, mood and quality of life after 3 and 12 weeks in people with prediabetes and type 2 diabetes and to assess possible mediators, compared to regular sleep habits. Methods In this randomized controlled trial, 60 people with prediabetes or type 2 diabetes with > 1 h social jetlag will be recruited. The intervention consists of bright light therapy (5000 lx) emitted by Vitamine-L (Lumie, UK) for 30 min each morning, combined with the advice to follow sleep advance instructions and to wear bright light-dimming goggles every evening for a period of 3 weeks. The control group adheres to their regular sleep habits and conditions. The primary outcome is glycated hemoglobin (HbA1c) after 12 weeks comparing the intervention and control in an intention-to-treat analysis. Secondary outcomes at 3 and 12 weeks are (1) social jetlag; (2) insulin sensitivity, fasting blood glucose, glucose-lowering medication use, and frequency of perceived hypoglycemia; (3) metabolic outcomes, including body mass index (BMI), waist circumference, body fat percentage, and blood pressure; (4) mood, including depression, fatigue and anxiety (measured with questionnaires); and (5) quality of life measured using EQ5D questionnaire. To assess other factors that might play a role as possible mediators, we will measure (para)sympathetic nervous system activity assessed with ECGs and electrochemical skin conductance tests, sleep quality and sleep phase distribution assessed with a sleep measuring headband (ZMax), the Dim Light Melatonin Onset in saliva samples (in a subgroup) at 3 and 12 weeks, the feeling of satiety and satiation with a 10-cm visual analog scale (VAS), diet using a food frequency questionnaire, and physical activity using an accelerometer (ActiGraph). Discussion Social jetlag can contribute to poorer glycemic control and metabolic control in those with type 2 diabetes. With this intervention, we aim to reduce social jetlag and thereby improve glycemic and metabolic control. This could offer a way to improve overall population health and to reduce the disease burden of type 2 diabetes. Trial registration ISRCTN registry ISRCTN11967109 . Registered on 9 May 2024. |
