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Article Excerpt
ALTHOUGH THE EFFECTS OF even low doses of alcohol on occupational performance such as ship handling are documented (e.g., Howland et al., 2000, 2001), the effects of an evening of heavy drinking on performance the next morning (residual alcohol effects) are less clear. Several investigators have used flight-training simulators to conduct placebo-controlled trials on the residual effects of alcohol intoxication (.10 g% breath alcohol concentration [BrAC]) in aircraft pilots. Collins failed to find residual alcohol effects on simulated aircraft flight performance (Collins, 1980; Collins and Chiles, 1980), but other studies involving simulated flight did find impairment after an evening of alcohol intoxication (Morrow et al., 1990, 1991, 1993; Taylor et al., 1994; Yesavage and Leirer, 1986; Yesavage et al., 1994). Decrements in aircraft flight performance were seen particularly among older pilots for acute effects (Yesavage et al., 1994) but only among younger pilots 8 hours later (Taylor et al., 1994). Automobile simulator performance was impaired the morning after alcohol consumption, when average BrAC was just below .04 g% (Tornos and Laurell, 1991). Wolkenberg et al. (1975) found residual effects of alcohol (after doses ranging from .065 to .175 g% BrAC) in a simulated industrial work situation up to 18 hours after ingestion on reaction time, motor performance, and motor sensory skills. Streufert et al. (1995) studied residual alcohol effects (.10 g% BrAC the evening before, g% BrAC at testing) on executive decision making using computer-based economic or environmental disaster scenarios but did not show any deterioration of functioning despite hangover discomfort. Thus, studies of residual alcohol effects on simulated occupational performance have shown inconsistent results.
Another way in which residual alcohol effects have been studied has been with the use of standardized cognitive or psychomotor tests to determine the exact type of cognitive process affected. A number of studies have failed to document adverse effects of heavy drinking on next-day performance as measured by some of these tests. No impairment was found on a divided attention task 12 hours postintoxication (Lemon et al., 1993); on a battery of behavioral tasks the morning following heavy drinking (Chait and Perry, 1994); in cognition or manual dexterity the day after 1.4 g ethanol/kg body weight (Takala et al., 1958); on psychomotor performance the morning after .10 g% BrAC (Finnigan et al., 1998); in immediate recall, recognition, or vigilance the day after 1.4 g/kg (Verster et al., 2003); or on short-term memory and reaction time (McCaul et al., 1991). On the other hand, impairment in delayed recall and lower subjective alertness were found the morning after 1.4 g/kg (Verster et al., 2003), and impaired visual, memory, and intellectual process scales of a neuropsychological battery were found 13-15 hours after 1.5 g/kg (Kim et al., 2003). Inconsistencies among studies finding effects or no effects may be the result of factors such as the kind of performance measured, amount of alcohol administered, degree of tolerance to alcohol, age and experience of participants, and whether or not participants performed with positive BrACs. Finnigan et al. (1998) noted that participants usually drank more than the study amount; therefore tolerance may have contributed to their lack of effects. Also, because a number of studies tested residual effects before BrAC returned to near zero, participants might not have been experiencing true residual effects. Further, the unsophisticated tests used in some of these studies may be less sensitive to impairing effects of a previous evening's heavy drinking than are batteries of more sophisticated cognitive tasks or many of the more complex and realistic occupational performance measures.
When an evening of heavy drinking disrupts next-day performance, it is possible that the effects are due to alcohol disrupting the quality of sleep. While 1.0 g/kg taken within 30-45 minutes of bedtime results in falling asleep more quickly (reduced sleep onset latency), it also makes sleep more shallow and disturbed during the second half of the night (Gillin and Drummond, 2000; Knowles et al., 1968; MacLean and Cairns, 1982; Rundell et al., 1972; Williams et al., 1983), although total sleep time is generally not affected (Roehrs et al., 1991). The fatigue or sleepiness that might result from the fragmented sleep may be a mechanism by which heavy drinking affects next-day performance. Studies to date have assessed sleep quality by means of subjective report the morning after an evening of heavy drinking (e.g., Finnigan et al., 1998; Lemon et al., 1993), but no study has examined sleep disruption as a mechanism of next-day performance impairment. Although polysomnography is the preferred way to assess sleep disruption, subjective measures are more economical and expedient and are highly correlated with polysomnography measures of sleep in healthy volunteers without sleep complaints (Armitage et al., 1997).
The subjective experience of hangover symptoms may or may not be correlated with performance deficits. Hangover is a set of subjective physical and mental symptoms occurring when blood alcohol concentration (BAC) is falling after an episode of heavy drinking, that peaks about the time BAC reaches g%, and that may last up to 24 hours thereafter (Swift and Davidson, 1998). The few experimental investigations of hangover symptoms, mostly conducted in the 1970s, determined a general set of subjective symptoms (primarily thirst, fatigue, general malaise, nausea, loss of appetite, and headache) detectable at 8:00 AM after heavy drinking in the evening but not 2 or more hours later. Observer ratings of signs of hangover (e.g., paleness, tremor, perspiration, nystagmus) were not significantly increased the morning after evening heavy drinking (Chapman, 1970; Seppala et al., 1976; Ylikahri et al., 1974). Although some survey instruments have been developed (e.g., Slutske et al., 2003) and some acute studies have used items assessing withdrawal rather than hangover (e.g., McCaul et al., 1991; Span and Earlywine, 1999) or a mixture of hangover symptoms and cognitive reactions such as guilt (e.g., Span and Earlywine, 1999), no measure of acute hangover symptoms has been psychometrically established. Therefore, the present study investigated the reliability of a modified version of an acute hangover instrument used in a previous study (Roehrs et al., 1991), most of the items of which had been previously validated (Chapman et al., 1970; Roehrs et al., 1991, Ylikahri et al., 1974).
The present study provided maritime academy engineering cadets with a baseline evening of placebo beverage consumption followed by an evening of randomization to alcohol or placebo beverage consumption. Each evening was followed by a morning of assessment of residual alcohol effects using measures of marine power plant simulator performance and ratings of hangover, sleep quality, and performance self-evaluation. Power plant simulator performance is sensitive...
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