Alcohol effects
Just a few non-personal comments from a medical point of view.
There are health benefits to alcohol consumption. The effect is limited, however, to no more than 2 standard drinks per day, with a minimum of 2 alcohol-free days per week. Any more than that, and the adverse health effects outweigh any benefit. The WHO limits for healthy drinking (ie. not causing long term damage) are, for men, 4 standard drinks per day, and for women, 2 per day, also with a minimum of 2 alcohol-free days per week.
The performance effects of alcohol are well known, and I won't go into it here. There is also a lot of evidence of the LATE performance effects, long after the blood alcohol has returned to zero. For example, the vestibular effects after a big night are measurable for at least 36hours after the blood alcohol returns to zero.
There have been studies on the cognitive effects.
One that is easy to obtain is:
Yesavage, J.A. and Leirer, V.O. “Hangover Effects on Aircraft Pilots 14 Hours After Alcohol Ingestion: A Preliminary Report in American Journal Psychiatry 143:12, December 1986 p 1546-1550.
It found, “Using a repeated measure counterbalanced design, the authors had 10 [US] Navy P3-C Orion pilots fly two carefully designed simulated flights under control (no hangover) and hangover conditions. For the control condition, pilots drank no alcohol within 48 hours before the simulated flight. For the hangover condition, they flew 14 hours after drinking enough ethanol mixed with diet soft drinks (the equivalent of 6-7 standard drinks) to attain a blood alcohol concentration of 100 mg/dl [BAC of 0.1%]. Pilot performance was worse in the hangover condition on virtually all measures but significantly worse on three of six variance measures". The performance decrement has been attributed to alcohol’s impairment of both working memory, and the ability to divide attention between tasks. Alcohol also reduces the ability to perform non-routine acts, and has an even greater effect when an alternative, non-typical response is required. In terms of pilot performance, this suggests that in emergency conditions, the adverse performance effects of alcohol may be most pronounced.
It has also been shown in a number of scientific studies that, particularly at higher doses, the consumption of alcohol before sleep, causes increased wake periods, or light Stage 1 sleep, especially during the second half of the sleep period. Alcohol is also a diuretic, resulting in increased urine production, and frequently hence the need to urinate during the night, further disrupting sleep.
At levels of alcohol significantly below that which could have been expected following the consumption of 6 standard drinks, next- day alertness and divided-attention performance haves been measured to be impaired. This illustrates that alcohol consumption can directly impair daytime alertness and performance through disruptive effects on sleep.
No one is saying don't enjoy a drink. 1 or 2 drinks 8 hours before reporting for duty will be gone in those with normal alcohol metabolism. But it is also important to remember that just because you have a zero blood alcohol after a large number of drinks doesn't mean that you won't be significantly impaired.
Cheers,
BM