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Sleep experts Johan Verbraecken and Inge Declercq identified nine less predictable factors that can worsen sleep quality. The factors were presented alongside more familiar influences such as coffee and blue light.
1 source
Neurologist Inge Declercq and lighting expert Jan Denneman said that the amount of light people receive is important for their health, alongside healthy food, exercise and sufficient sleep. They wrote the book *The Light Diet*, in which they explain where people may go wrong and offer advice, including that using night mode on a mobile phone does not solve everything.