All I can say is if I read from my iPad or iPhone in bed, it can keep me up nearly indefinitely. If I read in my e-ink Kindle with a front light, I will get so

All I can say is if I read from my iPad or iPhone in bed, it can keep me up nearly indefinitely. If I read in my e-ink Kindle with a front light, I will get so sleepy so fast I can only get through a few pages each night.