Sleep circadian factors

B. Work-Related Issues That Affect Sleep and Circadian Factors... 

Predictability provides an individual with the opportunity to plan, whether for work, recovery requirements, or home activities. When possible, schedule stability provides more consistent circadian cues and the opportunity to create individual patterns and habits that minimize the physiological disruptions. Modem work demands, especially 24/7 requirements, are often associated with overtime, which may be elective or on occasions required. Extending work has the potential to increase the continuous hours awake, be affected by circadian factors by working through a window of circadian low, and contribute to both acute sleep loss and a cumulative sleep debt. The timing and amount of overtime and whether it is elective or required, can all affect the level of physiological disruption. 

As health professionals have become more aware of the importance of sleep, the treatment of sleep disorders has received increasing attention. As a result, new drugs have become available on the market and new information has become available on the role of sleep factors, the homeostatic regulation of sleep, circadian rhythm, chronotherapy, the role of immunology, and genetics of sleep disorders. The new knowledge will further enhance the ability of health professionalsto develop new medicines for the treatment of sleep disorders. 

One of us examined the timely use of three factors (melatonin treatment, exposure to light, physical exercise) to hasten the resynchronization of the sleep-wake cycle in a group of elite sports competitors after a transmeridian flight across 12 time zones (Cardinali et al. 2002). Outdoor light exposure and physical exercise were used to cover symmetrically the phase delay and the phase advance portions of the phase-response curve. Melatonin taken at local bedtime helped to resynchronize the circadian oscillator to the new time. Individual actograms taken from sleep log data showed that all subjects became synchronized in their sleep to the local time in 24-48 h, well in advance of what would be expected in the absence of any treatment (Cardinali et al. 2002). More recently, a retrospective analysis of the data obtained from 134 normal volunteers flying the Buenos Aires - Sydney transpolar route in the past 9 years was published this further supports such a role for exogenous melatonin in resynchronization of sleep cycles (Cardinal et al. 2006). 

Ishida With respect to Ufespan, work by Paul Shaw on cjfi mutant flies showed that they became very sensitive to desiccation and sleep stress (Shaw et al 2002). cjfi flies died early after sleep deprivation. So the molecular mechanism of lifespan might be related to that of the circadian system. But another possibility is that BMALl and CLOCK regulate many other output factors, such as stress-sensitive proteins. 

Insomnia is a complaint, not a disease. The causes of insomnia are classified both in the DSM-IV for psychiatrists and in the International Classification of Sleep Disorders for sleep experts (Table 8—3). Insomnia can be a primary problem, or it can be secondary to medical or psychiatric disorders or to medications. Insomnia can also be due psychophysiological factors such as stress or to circadian rhythm distur-... 

The 24/7 requirements of RTC Ops can affect both sleep and circadian rhythms. The scientific literature suggests that at least four core physiological factors can be affected by, or play a role in, work-related alertness, safety, and performance... 

These factors include sleep, continuous hours of wakefulness, circadian rhythms, and sleep disorders. 

RTC Ops can affect all of these physiological factors acute sleep loss and cumulative sleep debt, hours of continuous wakefulness, circadian/time-of-day, and sleep disorders. Diverse work requirements lead inevitably to physiological disruptions and subsequent effects on waking alertness, safety, and performance. 

Figures 1 through 4 portray some of the societal, organizational, operational, and individual issues associated with managing alertness. Each level identifies only some example issues and factors that can affect sleep loss, circadian...

Existing mathematical models predicting cognitive readiness/performance from sleep/wake history are based on the interaction of three factors. These factors are sleep homeostasis, circadian rhythm, and sleep inertia (12). Three-factor models successfully predict performance effects of acute, total sleep deprivation and... 

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