It's well known that sleep-deprived people have shorter and fewer REM sleep periods. So, presumably sleep deprived-people likely have fewer dreams. That doesn

It's well known that sleep-deprived people have shorter and fewer REM sleep periods. So, presumably sleep deprived-people likely have fewer dreams. That doesn't necessarily mean they'd remember fewer of them, but it wouldn't be a big stretch. Personally, the amount of sleep I get correlates strongly with the amount that I remember dreams. I suspect caffeine intake is correlated with sleep deprivation bidirectionally. People who don't have the free time to afford enough sleep tend to drink more caffeine to compensate, and people who drink more caffeine tend to have lower quality of sleep. So, I suspect that it's the length of sleep that's really the relevant factor here. I've also heard from several friends that nicotine patches cause very vivid dreams almost every night. Caffeine certainly isn't nicotine, but the case for stimulants in general causing a lack of dreams. Maybe caffeine is an outlier in this regard, but, like I said, I suspect caffeine intake is primarily a confounder for sleep deprivation.