| 1. |
- Holmbäck, Ulf, et al.
(författare)
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The Human Body May Buffer Small Differences in Meal Size and Timing during a 24-h Wake Period Provided Energy Balance Is Maintained
- 2003
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Ingår i: Journal of Nutrition. - : Elsevier BV. - 0022-3166 .- 1541-6100. ; 133:9, s. 2748-55
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Tidskriftsartikel (refereegranskat)abstract
- Because approximately 20% of the work force in the industrialized world have irregular working hours, it is pertinent to study the consequences of eating at irregular, especially nighttime hours. We studied the postprandial responses during nocturnal fasting vs. eating throughout a 24-h wake period. Seven healthy males were studied twice in a crossover design. After a 6-d diet adjustment period [high fat diet, 45 energy percent (en%) fat, 40 en% carbohydrates)] with sleep from 2300 to 0700 h, the men were kept awake for 24 h at the metabolic ward and given either 6 isoenergetic meals, i.e., every 4 h (N-eat) or 4 isoenergetic meals from 0800 to 2000 h followed by a nocturnal fast (N-fast), with the same 24-h energy intake. Energy expenditure, substrate utilization, activity, heat release, body temperature and blood variables were measured over 24 h. Energy expenditure and blood glucose, triacylglycerol, insulin and glucagon concentrations were lower and nonesterified fatty acids concentrations were higher during the nocturnal fast than during nocturnal eating (P < 0.05); however, no 24-h differences between the protocols were apparent. Nocturnal fasting slightly altered the secretory patterns of the thyroid hormones and cortisol (P < 0.05). We found no clear indication that it would be more favorable to ingest few larger daytime meals than smaller meals throughout the 24-h period. The body seems to be able to buffer small differences in meal size and timing provided energy balance is maintained.
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| 2. |
- Anund, Anna, et al.
(författare)
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Driver impairment at night and its relation to physiological sleepiness.
- 2008
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Ingår i: Scand J Work Environ Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 34:2, s. 142-50
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Tidskriftsartikel (refereegranskat)abstract
- Driver impairment at night and its relation to physiological sleepiness.Anund A, Kecklund G, Peters B, Forsman A, Lowden A, Akerstedt T.VTI, S-581 95 Linköping, Sweden. anna.anund@vti.se.OBJECTIVES: Studies of devices detecting sleepiness need reference points of physiological sleepiness. The present study sought to validate the Karolinska drowsiness score (KDS) as an indicator of physiological sleepiness against driving impairment and eye blink duration during a 45-minute drive in an advanced moving-base driving simulator. METHODS: Data from 19 persons were used in the analysis. Electrooculography, electroencephalography, and electromyography were administered continuously. Physiological sleepiness was quantified by scoring the percentage (0-100%) of the scoring epoch with alpha and theta activity and slow eye movements (KDS). Lateral position and speed were used as measures of driving behavior. Lane departure was defined as two wheels touching the lane markers. Blink duration was used as a secondary indicator of sleepiness. RESULTS: The results showed that, for young drivers, sleepiness increased with time in the task with higher levels. The variability of the lateral position and the mean and variability of the blink duration significantly changed when sleepiness increased to KDS >/=20%. Furthermore, there was an increase in the risk of lane departure for KDS >/=30%. CONCLUSIONS: The results suggest that KDS scoring is a reasonable procedure for estimating physiological sleepiness under conditions of driving. The results also indicate that a younger age is associated with greater sensitivity to sleepiness at the wheel.
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| 3. |
- Arnetz, Bengt B., et al.
(författare)
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The Effects of 884 MHz GSM Wireless Communication Signals on Self-reported Symptoms and Sleep : An Experimental Provocation Study
- 2007
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Ingår i: PIERS online. - 1931-7360. ; 3:7, s. 1148-1150
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Tidskriftsartikel (refereegranskat)abstract
- In the current study we assessed possible effects of prolonged (3 hours) exposure to 884 MHz GSM wireless communication signals on self-reported symptoms, cognitive function, and electroencephalographically (EEG) recorded sleep. The study group consisted of 36 women and 35 men. Twenty-two women and sixteen men reported symptoms they specifically related to mobile phone use (SG). The rest of the participants reported no mobile phone-related symptoms (NG). Potential participants volunteering for the study were evaluated by physicians, including some biochemical assessments, to rule out medical conditions that could interfere with study variables of interest. Once selected, participants spent three different sessions in the laboratory. The habituation session was followed by two subsequent sessions. In these subsequent sessions, subjects were either exposed to sham exposure (sham) or 884 MHz GSM wireless communication signals for 3 hours (an average of 1.4 W/kg including periods of DTX and Non-DTX. Exposure directed to the left hemisphere). Data was collected before, during and following the exposure/sham sessions. Data collected included self-reported symptoms, including headache, cognitive function, mood, and electroencephalographic recordings. During actual exposure, as compared to sham exposure, sleep initiated one hour after exposure was affected. There was a prolonged latency to reach the first cycle of deep sleep (stage 3). The amount of stage 4 sleep was also decreased in exposed subjects. NG subjects reported more headaches during exposures vs. sham exposure. Neither group (SG and NG) was able to detect the true exposure status more frequently than by chance alone. The study indicates that during laboratory exposure to 884 MHz wireless signals, components of sleep, believed to be important for recovery from daily wear and tear, are adversely affected. Moreover, participants that otherwise have no self-reported symptoms related to mobile phone use, appear to have more headaches during actual radiofrequency exposure as compared to sham exposure. However, subjects were not able to detect the true exposure status more often than would have been expected by statistical chance alone. Additional self-reported findings, biochemical, performance and electrophysiological data are currently being analyzed. Possible health implications from the findings will also be further explored.
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| 4. |
- Eckerberg, Berndt, et al.
(författare)
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Melatonin treatment effects on adolescent students' sleep timing and sleepiness in a placebo-controlled crossover study
- 2012
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Ingår i: Chronobiology International. - : Informa UK Limited. - 0742-0528 .- 1525-6073. ; 29:9, s. 1239-1248
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Tidskriftsartikel (refereegranskat)abstract
- During the last few decades, the incidence of sleep-onset insomnia, due to delay of circadian phase, has increased substantially among adolescents all over the world. We wanted to investigate whether a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing in teenagers. Twenty-one students, aged 14-19 yrs, with sleep-onset difficulties during school weeks were recruited. The study was a randomized, double blind, placebo (PL)-controlled crossover trial, lasting 5 wks. During the first 6 d in wks 2 and 4, the students received either PL or melatonin (1 mg) capsules between 16:30 and 18:00 h. During the first 6 d of wk 5, all students received melatonin. Wks 1 and 3 were capsule-free. In the last evening of each week and the following morning, the students produced saliva samples at home for later melatonin analysis. The samples were produced the same time each week, as late as possible in the evening and as early as possible in the morning. Both the student and one parent received automatic mobile text messages 15 min before saliva sampling times and capsule intake at agreed times. Diaries with registration of presumed sleep, subjective sleepiness during the day (Karolinska Sleepiness Scale, KSS) and times for capsule intake and saliva samplings were completed each day. Primary analysis over 5 wks gave significant results for melatonin, sleep and KSS. Post hoc analysis showed that reported sleep-onset times were advanced after melatonin school weeks compared with PL school weeks (p < .005) and that sleep length was longer (p < .05). After the last melatonin school week, the students fell asleep 68 min earlier and slept 62 min longer each night compared with the baseline week. Morning melatonin values in saliva diminished compared with PL (p < .001) and evening values increased (p < .001), indicating a possible sleep phase advance. Compared with PL school weeks, the students reported less wake up (p < .05), less school daytime sleepiness (p < .05) and increased evening sleepiness (p < .005) during melatonin weeks. We conclude that a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing and make the students more alert during school days even if they continued their often irregular sleep habits during weekends.
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| 5. |
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| 6. |
- Holmbäck, Ulf, et al.
(författare)
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Metabolic responses to nocturnal eating in men are affected by sources of dietary energy
- 2002
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Ingår i: Journal of Nutrition. - : The American Society for Nutritional Sciences. - 0022-3166 .- 1541-6100. ; 107, s. 121-
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Tidskriftsartikel (refereegranskat)abstract
- Because night work is becoming more prevalent, we studied whether feeding at different times of a 24-h period would elicit different metabolic responses and whether dietary macronutrient composition would affect these responses. Seven men (26-43 y, 19.9-26.6 kg/m(2)) consumed two isocaloric diets, in a crossover design. The diets were a high carbohydrate (HC) diet [65 energy % (E%) carbohydrates, 20E% fat] and a high fat (HF) diet (40E% carbohydrates, 45E% fat). After a 6-d diet-adjustment period, the men were kept awake for 24 h and the food (continuation of respective diet) was provided as six isocaloric meals (i.e., every 4 h). Energy and substrate turnover, heart rate, mean arterial pressure (MAP), blood glucose, triacylglycerol (TAG), nonesterified fatty acid (NEFA) and glycerol were measured throughout the 24-h period. Significantly higher energy expenditure and NEFA concentration, and lower blood glucose and TAG concentrations were observed when the men consumed the HF diet than when they consumed the HC diet. Significant circadian patterns were seen in body and skin temperature (nadir, 0400-0500 h). When the men consumed the HF diet, significant circadian patterns were seen in fat oxidation (nadir, 0800-1200 h; plateau, 1200-0800 h), heat release (nadir, 0800-1200 h; plateau, 1600-0800 h), heart rate (nadir, 0000 h), blood glucose (nadir, 0800-1200 h; peak, 0000-0400 h), NEFA (nadir, 0800-1200 h; peak, 1200-2000 h) and TAG (nadir, 0800-1200 h; peak, 0400-0800 h) concentrations. Energy expenditure, carbohydrate oxidation, MAP and glycerol concentration did not display circadian patterns. Unequal variances eradicated most circadian effects in the HC-diet data. The increased TAG concentration in response to feeding at 0400 h might be involved in the higher TAG concentrations seen in shift workers. Distinct macronutrient/circadian-dependent postprandial responses were seen in most studied variables.
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| 7. |
- Kaida, Kaida, et al.
(författare)
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Performance prediction by sleepiness-related subjective symptoms during 26-hour sleep deprivation
- 2008
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Ingår i: Sleep and Biological Rhythms. - : Springer Science and Business Media LLC. - 1446-9235 .- 1479-8425. ; 6:4, s. 234-241
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Tidskriftsartikel (refereegranskat)abstract
- Sleepiness is a major cause of lower productivity and higher risk of accidents in various work situations. Developing sleepiness monitoring techniques is important to improve work efficiency and to reduce accident risk, so that people can take a rest/break in appropriate timing before an accident or a mistake occurs. The aims of the present study are (1) to explain subjective sleepiness using sleep-related symptoms, and (2) to examine which symptoms are useful to predict performance errors. Participants were healthy paid volunteers (six males, six females; mean +/- SD, 31.5 +/- 10.74 years). Participants took part in 26-h sleep deprivation. During sleep deprivation, they carried out several performance tasks every 3 h and an hourly rating of questionnaires to evaluate subjective symptoms including two types of Karolinska sleepiness scale (KSS). The present study confirmed that performance errors can be predicted by subjective symptoms. While mental fatigue was correlated to KSS scores linearly, eye-related subjective symptoms showed quadratic correlations to KSS. By taking into consideration this noteworthy relationship between subjective symptoms and sleepiness, more accurate introspection of sleepiness and performance errors prediction (detection) may be possible.
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| 8. |
- Kecklund, Göran, et al.
(författare)
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20th International Symposium on Shiftwork and Working Time : Biological Mechanisms, Recovery, and Risk Management in the 24-h Society
- 2012
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Ingår i: Chronobiology International. - : Informa UK Limited. - 0742-0528 .- 1525-6073. ; 29:5, s. 531-536
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Tidskriftsartikel (refereegranskat)abstract
- This dedicated issue of Chronobiology International is devoted to the selected proceedings of the 20th International Symposium on Shift Work and Working Time held in Stockholm, Sweden, 28 June to 1 July 2011. It constitutes the fifth such issue of the journal since 2004 dedicated to the selected proceedings to the meetings of the Working Time Society. The key theme of the 20th Symposium was "Biological Mechanisms, Recovery, and Risk Management in the 24-h Society." The collection of papers of this dedicated issue represents the best of contemporary research on the effects of night and rotating shift schedules on worker health and safety. The contents cover such topics as sleep restriction, injuries, health, and performance of night work and rotating shiftwork, plus light treatment as a countermeasure against the circadian disruption of shiftwork. The majority of the papers are observational field studies, including some of large sample size, and three studies are well-designed laboratory experiments. (Author correspondence: goran.kecklund@stress.su.se ).
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| 9. |
- Lowden, Arne, et al.
(författare)
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Assessment of a new dynamic light regimen in a nuclear power control room without windows on quickly rotating shiftworkers-effects on health, wakefulness, and circadian alignment : a pilot study
- 2012
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Ingår i: Chronobiology International. - : Informa UK Limited. - 0742-0528 .- 1525-6073. ; 29:5, s. 641-649
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to test whether a new dynamic light regime would improve alertness, sleep, and adaptation to rotating shiftwork. The illumination level in a control room without windows at a nuclear power station was ∼200 lux (straight-forward horizontal gaze) using a weak yellow light of 200 lux, 3000 K (Philips Master TLD 36 W 830). New lighting equipment was installed in one area of the control room above the positions of the reactor operators. The new lights were shielded from the control group by a distance of >6 m, and the other operators worked at desks turned away from the new light. The new lights were designed to give three different light exposures: (i) white/blue strong light of 745 lux, 6000 K; (ii) weak yellow light of 650 lux, 4000 K; and (iii) yellow moderate light of 700 lux, 4000 K. In a crossover design, the normal and new light exposures were given during a sequence of three night shifts, two free days, two morning shifts, and one afternoon shift (NNN + MMA), with 7 wks between sessions. The operators consisted of two groups; seven reactor operators from seven work teams were at one time exposed to the new equipment and 16 other operators were used as controls. The study was conducted during winter with reduced opportunities of daylight exposure during work, after night work, or before morning work. Operators wore actigraphs, filled in a sleep/wake diary, including ratings of sleepiness on the Karolinska Sleepiness Scale (KSS) every 2 h, and provided saliva samples for analysis of melatonin at work (every 2nd h during one night shift and first 3 h during one morning shift). Results from the wake/sleep diary showed the new light treatment increased alertness during the 2nd night shift (interaction group × light × time, p < .01). Time of waking was delayed in the light condition after the 3rd night shift (group × light, p < .05), but the amount of wake time during the sleep span increased after the 2nd night shift (p < .05), also showing a tendency to affect sleep efficiency (p < .10). Effects on circadian phase were difficult to establish given the small sample size and infrequent sampling of saliva melatonin. Nonetheless, it seems that appropriate dynamic light in rooms without windows during the dark Nordic season may promote alertness, sleep, and better adaptation to quickly rotating shiftwork. (Author correspondence: arne.lowden@stress.su.se ).
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| 10. |
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