Caffeine consumed late in the day disrupts the circadian clock, delays melatonin release, and reduces deep sleep quality.

“caffeine especially disrupts what's called compensatory sleep. So if you start changing your waking time and your to sleep time and you start using additional caffeine to offset the sleepiness that you're experiencing because of those late nights out, well, that's when you really start to disrupt not just your nighttime sleep, but your daytime compensatory sleep, so those naps. You also are disrupting the total architecture of sleep in the early morning hours.”

“caffeine consumed in the, gosh, even 12 but really eight to 10 hours, four hours prior to bedtime really disrupts the architecture of sleep.”

“I suppose the only thing is to remind people to not consume caffeine too close to bedtime, because even if you can fall asleep- [...] - it's going to disrupt the architecture of your sleep.”

“Caffeine consumed late in the day powerfully disrupts this clock. There's controlled laboratory studies that show that caffeine taken within about 3 hours of natural bedtime shifts the internal clock later by roughly 45 minutes to an hour. So this is like giving yourself a mini dose of jet lag every day. The result delayed melatonin release, disrupted sleep patterns, reduced deep sleep quality, and ultimately compromised health.”