Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

According to "common knowledge", morning/afternoon exercise is "good" for sleep (in the long run) and caffeine is bad (less so in the morning). However, both of these stimulate the brain; exercise gives a "runners high".

Does a long term caffeine intervention affect sleep? I can't seem to find a study on this topic. For exercise, we have this study, which references a few others (afternoon intervention): http://www.ncbi.nlm.nih.gov/pubmed/23946713

Why does it take several days/weeks for exercise to improve sleep? How/why does caffeine differ from exercise as a long-term "morning sleep stimulant"? One possible reason: Caffeine has a relatively long half-life of 4-6 hours, which means that up to 1/4 will still be there at night.

share|improve this question
The question implies that exercise as a stimulant is something which can be compared with caffeine as a stimulant which I think is poorly posed. Even if exercise gives similar effects to those that would be conferred by a stimulant, it is not a drug and cannot be classified as a stimulant. The "runner's high" is thought to be related to a whole different drug-like activity (opiods), which, ironically, would tend to promote sleep. –  Ryan Feb 11 at 4:02

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.