Pappa Smurf - It's well-known in medical circles that weed use slows down response and reaction times, long after it has been smoked.
Amongst chronic weed users, the ability to react swiftly to emergency situations is 100% impaired. They're permanently "chilled out".
THC stays in the bodys' fat cells and brain for up to 30 days, and continues to have an effect on multiple systems within the body.
Small amounts of alcohol also sharply and noticeably affect response and reaction times - even when alcohol consumers are convinced they "feel great".
I can recall a "swerve around the cones at speed" driving test, that was done with alcohol free drivers and those that had a BAC of around .04-.05%.
These imbibers were convinced they felt 100% and had no skills impairment whatsoever. They were stunned to find they had clipped cones on the test, while they were convinced they hadn't.
The major difference between alcohol and weed is that alcohol is cleared from the body at a faster rate than weed and there are no measureable alcohol levels after 12 hrs.
Whether there is still an effect on response and reaction times when one is suffering from an alcohol hangover, I couldn't say, because I've never seen any tests done on that specific basis.
I do know I have seen fatal road accidents where young men were killed on the road in the morning after a night of heavy drinking. In those cases, I'm fairly sure that sleep deprivation had more to do with the fatals than the BAC.
Either way, you're not doing yourself any favours by punishing your body and then promptly hopping into a car, plane, balloon, loco - or whatever you choice of a complex machine is - within 12 hrs, and expect to be able to perform high-intensity tasks, with the same reaction and response times as when you're completely unaffected by any drug.
Both weed and alcohol are drugs, they both have severe effects on the human system, even in small quantities. This has been medically recognised for decades.
My personal choice is to avoid consuming anything that might even slightly affect my performance skills the following day, even after a good sleep.
How Long Does Alcohol Stay in the Body?
How Long Does Marijuana Stay in Your System?