Sleep quality and quantity after sex will be confounded by caffeine and alcohol consumption and potential later/earlier onset of sleep following evening sexual activity. Even a well designed study using measuring devices will have to account for more variables to examine any effect.
Interesting point! As it happens I have a reasonably large dataset on my hands, with both self-reported and mobile EEG-based sleep. (I know it looks like I write about random autistic stuff but these posts are usually byproducts of actual empirical studies I'm doing.) Participants (N=180 with N=1192 nights at this point) report both sex and alcohol consumption during the day. They don't specifically record when these took place though, and I don't have caffeine data, but while I agree that people do drink a lot around having sex I think they don't really drink coffee. You are very right that people sleep about 9 minutes later after having sex, this is, however, not quite significant. After alcohol consumption, they do sleep about 45 minutes later though, which is p=10^-11. Sex has no significant effect on either self-reported (Groningen scale filled out the next morning) sleep quality or EEG-based sleep latency or sleep quality (wake after sleep onset and sleep efficiency). Alcohol reduces sleep onset latency by about 3 minutes (the mean here is ~15 minutes) which is highly significant but doesn't affect the other measures - I guess most of the time this was a glass of beer or something rather than total shitfacing. Controlling for alcohol consumption in the models doesn't really do anything with the sex coefficients (or the alcohol coefficients for that matter). The same if we control for bedtime - a later bedtime is associated with much better sleep by any measure (you actually are sleepy), but there is no residual effect for sex. So I think that even if you consider all this, sex doesn't really change sleep.
Sleep quality and quantity after sex will be confounded by caffeine and alcohol consumption and potential later/earlier onset of sleep following evening sexual activity. Even a well designed study using measuring devices will have to account for more variables to examine any effect.
And yes, I slept very well last night.
Interesting point! As it happens I have a reasonably large dataset on my hands, with both self-reported and mobile EEG-based sleep. (I know it looks like I write about random autistic stuff but these posts are usually byproducts of actual empirical studies I'm doing.) Participants (N=180 with N=1192 nights at this point) report both sex and alcohol consumption during the day. They don't specifically record when these took place though, and I don't have caffeine data, but while I agree that people do drink a lot around having sex I think they don't really drink coffee. You are very right that people sleep about 9 minutes later after having sex, this is, however, not quite significant. After alcohol consumption, they do sleep about 45 minutes later though, which is p=10^-11. Sex has no significant effect on either self-reported (Groningen scale filled out the next morning) sleep quality or EEG-based sleep latency or sleep quality (wake after sleep onset and sleep efficiency). Alcohol reduces sleep onset latency by about 3 minutes (the mean here is ~15 minutes) which is highly significant but doesn't affect the other measures - I guess most of the time this was a glass of beer or something rather than total shitfacing. Controlling for alcohol consumption in the models doesn't really do anything with the sex coefficients (or the alcohol coefficients for that matter). The same if we control for bedtime - a later bedtime is associated with much better sleep by any measure (you actually are sleepy), but there is no residual effect for sex. So I think that even if you consider all this, sex doesn't really change sleep.