If you’re a caffeine drinker, you have probably received the advice to stop drinking caffeine by about noon to avoid any interference with your sleep. But why does coffee interfere with sleep? Studies suggest that caffeine impacts the chemical in our bodies called adenosine. According to a recent study published in PubMed, “The accumulation of adenosine is strongly correlated with the need for sleep and the detection of sleep pressure is antagonised by caffeine.” Another study notes that our circadian rhythm is highly impacted and regulated by light. Interestingly, in mice studies, it seems that “caffeine interferes with the ability of the circadian clock to respond normally to light.” [2] So what can you do to not interfere with your body’s sleep cycle while still enjoying caffeine? We learned from Dr. Michael Breus, The Sleep Doctor, on the SuperAge podcast, that caffeine has a half life of about 6-8 hours. That means that 6-8 hours after you consume caffeine, the stimulant effects are reduced by ½. While there is some variability depending on each individual, Dr. Breus explains that if you finish your last cup of coffee by 2pm, you should not have an issue falling asleep by 10:30pm. [3]
[1] https://pubmed.ncbi.nlm.nih.gov/33837202/
[2] https://pubmed.ncbi.nlm.nih.gov/30033847/
[3] https://thesleepdoctor.com/2017/08/31/caffeine-causing-sleeplessness/