Effects of alertness management training on sleepiness among long-haul truck drivers: A randomized controlled trial.

Education is a frequently recommended remedy for driver sleepiness in occupational settings, although not many studies have examined its usefulness. To date, there are no previous on-road randomized controlled trials investigating the benefits of training on sleepiness among employees working in road transport. To examine the effects of an educational intervention on long-haul truck drivers' sleepiness at the wheel, amount of sleep between work shifts, and use of efficient sleepiness countermeasures (SCM) in association with night and non-night shift, a total of 53 truck drivers operating from southern Finland were allocated into an intervention and a control group using a stratified randomization method (allocation ratio for intervention and control groups 32:21, respectively). The intervention group received a 3.5-hour alertness management training followed by a two-month consultation period and motivational self-evaluation tasks two and 4-5 months after the training, while the control group had an opportunity to utilize their usual statutory occupational health care services. The outcomes were measured under drivers' natural working and shift conditions over a period of two weeks before and after the intervention using unobtrusive data-collection methods including the Karolinska Sleepiness Scale measuring on-duty sleepiness, a combination of actigraphy and a sleep-log measuring sleep between duty hours, and self-report questionnaire items measuring the use of SCMs while on duty. The data analysis followed a per-protocol analysis. Results of the multilevel regression models showed no significant intervention-related improvements in driver sleepiness, prior sleep, or use of SCMs while working on night and early morning shifts compared to day and/or evening shifts. The current study failed to provide support for a feasible non-recurrent alertness-management training being effective remedy for driver sleepiness in occupational settings. These results cannot, however, be interpreted as evidence against alertness management training in general but propose that driver education is not a sufficient measure as such to alleviate driver sleepiness.

Sleepiness, sleep, and use of sleepiness countermeasures in shift-working long-haul truck drivers.

Driver sleepiness is a prevalent phenomenon among professional drivers working unconventional and irregular hours. For compromising occupational and traffic safety, sleepiness has become one of the major conundrums of road transportation. To further elucidate the phenomenon, an on-road study canvassing the under-explored relationship between working hours and sleepiness, sleep, and use of sleepiness countermeasures during and outside statutory rest breaks was conducted. Testing the association between the outcomes and working hours, generalized estimating equations models were fitted on a data collected from 54 long-haul truck drivers (mean 38.1 ± 10.5 years, one female) volunteering in the 2-week study. Unobtrusive data-collection methods applied under naturalistic working and shift conditions included the Karolinska Sleepiness Scale (KSS) measuring sleepiness, a combination of actigraphy and sleep-log measuring sleep, and self-report questionnaire items incorporated into the sleep-log measuring the use of sleepiness countermeasures during and outside statutory rest breaks. Drivers' working hours were categorized into first and consecutive night, morning and day/evening shifts based on shift timing. The results reveal severe sleepiness (KSS≥7) was most prevalent on the first night (37.8%) and least on the morning (10.0%) shifts. Drivers slept reasonably well prior to duty hours, with main sleep being longest prior to the first night (total sleep time 7:21) and shortest prior to the morning (total sleep time 5:43) shifts. The proportion of shifts whereby drivers reported using at least one sleepiness countermeasure outside statutory rest breaks was approximately 22% units greater for the night than the non-night shifts. Compared to the day/evening shifts, the odds of severe sleepiness were greater only on the first night shifts (OR 6.4-9.1 with 95% confidence intervals, depending on the statistical model), the odds of insufficient daily sleep were higher especially prior to the consecutive night shifts (OR 3.5 with 95% confidence intervals), and the odds of using efficient sleepiness countermeasures outside statutory rest breaks were greater on the first as well as consecutive night shifts (OR 4.0-4.6 with 95% confidence intervals). No statistically significant association was found between shift type and use of efficient sleepiness countermeasures during statutory rest breaks. In all, the findings demonstrate marked differences in the occurrence of severe sleepiness at the wheel, sleep preceding duty hours, and the use of sleepiness countermeasures between different shift types. In addition, although drivers slept reasonably well in connection with different shift types, the findings imply there is still room for improvement in alertness management among this group of employees.

TRIB1 constitutes a molecular link between regulation of sleep and lipid metabolism in humans.

Epidemiological studies show association between sleep duration and lipid metabolism. In addition, inactivation of circadian genes induces insulin resistance and hyperlipidemia. We hypothesized that sleep length and lipid metabolism are partially controlled by the same genes. We studied the association of total sleep time (TST) with 60 genetic variants that had previously been associated with lipids. The analyses were performed in a Finnish population-based sample (N = 6334) and replicated in 2189 twins. Finally, RNA expression from mononuclear leucocytes was measured in 10 healthy volunteers before and after sleep restriction. The genetic analysis identified two variants near TRIB1 gene that independently contributed to both blood lipid levels and to TST (rs17321515, P = 8.92(*)10(-5), Bonferroni corrected P = 0.0053, ß = 0.081 h per allele; rs2954029, P = 0.00025, corrected P = 0.015, ß = 0.076; P<0.001 for both variants after adjusting for blood lipid levels or body mass index). The finding was replicated in the twin sample (rs17321515, P = 0.022, ß = 0.063; meta-analysis of both samples P = 8.1(*)10(-6), ß = 0.073). After the experimentally induced sleep restriction period TRIB1 expression increased 1.6-fold and decreased in recovery phase (P = 0.006). In addition, a negative correlation between TRIB1 expression and slow wave sleep was observed in recovery from sleep restriction. These results show that allelic variants of TRIB1 are independently involved in regulation of lipid metabolism and sleep. The findings give evidence for the pleiotropic nature of TRIB1 and may reflect the shared roots of sleep and metabolism. The shared genetic background may at least partially explain the mechanism behind the well-established connection between diseases with disrupted metabolism and sleep.

Interaction of age with shift-related sleep-wakefulness, sleepiness, performance, and social life.

It is not clear how the age-related changes in sleep are related to performance and subjective sleepiness at different time of the day. The aim of the present study was to study work shift related interactions of age with sleep-wakefulness, performance, and social life. A representative sample of aircraft maintenance workers in a continuous three-shift system was studied by a questionnaire (n = 275) and an on-site field (n = 49) study. In the field study, sleep length and quality and different ratings of social and other activities were studied with an actigraphy and a Pocket PC diary during 15 consecutive days. Subjective sleepiness (KSS) and vigilance performance (PVT) were registered at work. Although the shift type influenced the sleep, subjective sleepiness, performance, and social life, age was distinctly related only to shift-related changes in the amount of sleep, subjective sleepiness, and psychomotor vigilance. Night shifts were related with shorter sleep, decreased performance, and increased sleepiness. Although subjective sleepiness was greatest among the youngest (25-34 years) age group during the morning and the night shifts, the increase of performance lapses was higher among the middle-aged (35-49 years) and senior (50-58 years) groups during the night shifts compared to the youngest age group. According to the questionnaire, older shiftworkers also tended to perceive more frequently that subjective sleepiness decreases their work performance during the morning and night shifts. The results indicate of no direct link between age-related differences in subjective sleepiness and performance at night work. The shorter day sleep after the night shifts and higher deterioration of subjective and objective performance according to age urge on development of shift schedules aiming at lower fatigue levels during the night shifts.

The effect of an irregular shift system on sleepiness at work in train drivers and railway traffic controllers.

Sleepiness and fatigue are frequent problems in railway transportation with occasional monotony and irregular shift schedules. This study aimed at (1) studying the prevalence of severe sleepiness in shifts and (2) examining which shift and sleep-related factors were associated with the occurrence of severe sleepiness in an irregular shift system. A total of 126 randomly selected male train drivers (Tdrs) and 104 railway traffic controllers (Tcos) were investigated using questionnaires and sleep-wake diaries. A sleep diary was used to collect information on sleepiness at work and sleeping times during the 21 consecutive days of the study. The prevalence of severe sleepiness at work (i.e. Karolinska Sleepiness Scale 7 or higher) was modelled by a logistic regression analysis for repeated measurements (GEE) using different shift schedule related factors and sleep length as explanatory variables. Severe sleepiness was reported in 49% (Tdrs) and 50% (Tcos) of the night shifts and in 20% (Tdrs) and 15% (Tcos) of the morning shifts. The odds ratios showed that the risk for severe sleepiness was 6-14 times higher in the night shift and about twice as high in the morning shift compared with the day shift. Age affected the two occupational samples differently: with Tdrs increased age was associated with an additional 8% reduction of risk for severe sleepiness for each year of age, while the Tcos did not show any age dependency. Shift length increased the risk by 15% for each hour of the shift and main sleep period decreased the risk by 15% for each hour of the main sleep. The risk of severe sleepiness was not consistently related to the time-off period before the shifts. The results indicate that adjustments for shift timing, length and off-duty time, in addition to actions aiming at extending the main sleep period, would probably decrease severe sleepiness in railway transportation.

Promoting alertness with a short nap during a night shift.

The use of a short (< 1 h) nap in improving alertness during the early morning hours in the first night shift was examined under laboratory conditions. The study contained four experimental, non-consecutive night shifts with a nap of either 50 or 30 min at 01.00 or 04.00 hours. An experimental night shift without a nap served as a control condition. Each experimental shift was followed by daytime sleep. Fourteen experienced male shift workers went through all of the experimental conditions. The results showed that the naps improved the ability to respond to visual signals during the second half of the night shift. Physiological sleepiness was alleviated by the early naps, as measured 50 min after awakening, but not at the end of the shift. Subjective sleepiness was somewhat decreased by the naps. The naps produced sleep inertia which lasted for about 10-15 min. Daytime sleep was somewhat impaired by the 50 min naps. The study shows that a nap shorter than 1 h is able to improve alertness to a certain extent during the first night shift.

Mismatch negativity during objective and subjective sleepiness.

The mismatch negativity (MMN) and P3 of auditory event-related potentials were studied during subjectively and objectively (physiologically) defined sleepiness under optimal stimulus conditions for MMN elicitation. The MMN and P3 were elicited by either small or large unattended auditory deviants presented to the left ear. The participant's task was to detect either rare auditory targets presented to the right ear or rare changes in the light flashes. Eleven young adults served as participants in a nighttime experiment. The MMN declined especially at Fz and Cz but not so markedly at the right mastoid as either subjective or objective alertness decreased. The amplitude of P3 also decreased during sleepiness. The attenuation of the MMN was paralleled by a decline in behavioral performance. The results show that the MMN is attenuated by a decrease in alertness even before an actual sleep state is reached.

Precursors of the evoked K-complex in event-related brain potentials in stage 2 sleep.

The aim of the study was to examine precursors of the evoked K-complex as manifested in event-related brain potentials (ERPs) during stage 2 sleep. ERPs to infrequent deviant tones of 1100 and 2000 Hz and immediately preceding frequent standard tones of 1000 Hz were compared between trials containing and trials not containing a K-complex (KC trials, NO KC trials, respectively) to the deviant tones. The N350 wave to the deviant tones was markedly larger during the KC than during the NO KC trials. Also the P210 wave to the 2000 Hz deviant tone showed the same phenomenon. No definite evidence was found for the mismatch negativity-like deflection during the KC trials. ERPs to the standard tones presented immediately (625 ms) prior to the deviant tones showed a larger early positive wave during the KC trials than during the NO KC trials. No corresponding phenomenon could be observed for the identical standard tone presented 1250 ms prior to the deviant tones. In all, the results suggest that the sleeping brain is momentarily more responsive to incoming sensory events preceding a K-complex than preceding a no K-complex response to a stimulus.

Processing of auditory stimuli during tonic and phasic periods of REM sleep as revealed by event-related brain potentials.

The brain has been reported to be more preoccupied with dreams during phasic than during tonic REM sleep. Whether these periods also differ in terms of the processing of external stimuli was examined. Event-related brain potentials (ERPs) to a frequent standard tone of 1000 Hz (P = 97%) and infrequent deviant tones of 1100 and 2000 Hz (P = 1.5% for each) were recorded (n = 13) during wakefulness and nocturnal sleep. An ERP wave (called REM-P3) resembling a waking P3 wave was larger for the 2000 Hz deviant during tonic than during phasic REM sleep. Also the P210 wave was larger during tonic than during phasic REM sleep. A reliable mismatch negativity component appeared only in wakefulness. In summary, these results support the hypothesis that the brain is more 'open' for changes in an auditory input during tonic than phasic REM sleep.

Is the appearance of mismatch negativity during stage 2 sleep related to the elicitation of K-complex?

There is no convincing evidence for the occurrence of mismatch negativity (MMN) elicited by infrequent deviant tones in a homogenous tone stream during sleep in adult humans. Also the data presented here failed to show an MMN during any stage of sleep when event-related potentials (ERPs) were averaged across all trials of the same sleep stage. The aim of the study was to determine whether the MMN appearance during sleep is related to the variations in microstates of sleep that differ in terms of stimulus elicited phasic EEG events. The focus was on stage 2 sleep. The single responses to a deviant tone were classified into 3 types during stage 2 prior to averaging ERPs. These 3 response types included K-complex, other phasic EEG events and no visually discernible phasic EEG events. The results showed that an MMN-like deflection indeed appeared during stage 2 but only when the deviant tone also elicited a K-complex. This type of deflection was not seen when the deviant tone was presented without the intervening standard tones. This supports the hypothesis that a true MMN to the deviant tone was seen during stage 2 sleep preceding a K-complex.

Asymmetry of instructed motor response to auditory stimuli during sleep.

Previous studies have demonstrated that motor activity during sleep is lateralized to the nondominant hand. There are two basic theories concerning this phenomenon: 1) The nondominant hemisphere is nonspecifically more alert or responsive than the dominant one, and 2) the lateralization to the nondominant side is task specific, reflecting the spatially oriented mode of information processing that is responsible for movements during sleep. We examined the motor responses to auditory stimuli during waking and sleep of 10 right-handed healthy subjects, who were instructed to switch off a tone stimulus by pressing a transducer that was attached to each hand. Sleep stage scoring was performed according to Rechtschaffen and Kales's criteria. During wakefulness and in all stages of sleep, with and without alpha activity occurring after stimulus onset, the dominant hand was used more, but during nonrapid eye movement S1 sleep the difference was not statistically significant. When alpha activity was present in the electroencephalogram after stimulus onset, the responses were significantly more lateralized to the right hand than when there was no alpha activity. During an actimetric home recording of both wrists of the subjects, there was an excess of left-sided movements during sleep as compared to waking. The results do not support the idea that the right hemisphere is generally more responsive than the left during sleep. They are, however, in accordance with the hypothesis that spatial information processing is a crucial factor in the nondominant lateralization of spontaneous sleep movements.(ABSTRACT TRUNCATED AT 250 WORDS)