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Many office workers exhibit symptoms similar to Seasonal Depression even in summer months and this can have a significant impact on their work output and interaction with colleagues.
A review of the current research suggests that employers should be paying much more attention to the mental state of their employees and the time that they spend in the sunshine. Individuals working with computers in subdued lighting can be particularly affected and this can have real implications for those in call centres, computer programming, the media and animation. But all workers are potentially at risk.
Even on sunny days working adults may need 1000x more exposure to sunlight to stay mentally and physically healthy. Access to windows, and even the highest standards of office lighting, has little impact because it is biologically necessary to be exposed to bright sunlight or intense white light for a reasonable period first thing in the morning to suppress melatonin, the sleep hormone. If this does not happen, then the symptoms can include lethargy, low energy, carbohydrate craving, poor sleep patterns and depressed mood during the day.
The general lack of sunlight seems to cause a disruption of the body clock leading to symptoms similar to those experienced by shift workers or those suffering jet lag. There is also evidence that individuals living out of sequence with their body clock experience a condition being termed ‘Social jetlag’.
Bright Light Therapy can play a key role in managing the body clock and should be considered in the same way as ergonomic furniture to help those with body clock problems maintain their mood and productivity.
Why sunlight is important
All our lives are governed by circadian rhythms – our body clock. Circadian rhythms are the daily variations in bodily functions. The sleep/wake cycle, core body temperature, hormonal release and cognitive ability all exhibit a circadian rhythm. The biological process is governed by the sleep-inducing hormone melatonin. As daylight fades melatonin is secreted by the brain and we feel tired. Some 8-9 hours later, in most individuals, the level of melatonin reaches its minimum level and we wake. The exact mechanism is fairly new to science and is discussed later. However, the key fact is that the secretion of melatonin can be suppressed by exposure to sunlight or bright white light.
Although our body clocks are evolutionarily tuned to the hours of sunlight, not everyone works to the same time frame. Some people are naturally early risers, some are night owls. At the onset of puberty teenagers of both sexes experience a forward-shift such that they find it impossible to sleep until the early hours and cannot function properly before noon. Their inability to concentrate on their academic work and the incidence of morning accidents is thus biologically outside their control and not a factor of belligerent teenage behaviour. The converse happens at the onset of menopause and andropause and is the key reason why those in their 50s and beyond frequently begin to wake at 4-5am but can easily fall asleep in the early evening.
For many people, such as shift workers and long distance travellers, the effects of light and lack of sleep on body rhythms are well known. While the disruption of circadian rhythms is usually associated with shift workers, the BMA noted that it applies to any arrangements that require the individual to work when they would normally be sleeping, or to sleep when they would normally be awake. Researchers are talking of a more general condition that encompasses normal day to day situations. In essence, social jetlag describes the light induced conditions we experience when we live out of kilter with our body clock.
The Psychiatric Times noted that exposure to bright light is important for psychological well-being of healthy people. The report recommended that combined exposure to bright light and physical exercise can be especially effective for improving mood- and health-related quality of life. But in the modern industrial world, many people spend a lot of time indoors and commute in their car or public transport. As a result they are light-deprived and the problem is exacerbated by a sedentary lifestyle.
Dr. Dan Kripke, Professor of Psychiatry at the University of California, San Diego monitored the light exposure 150 middle-aged, middle-class adults 24 hours a day during a South California summer. Only half the adults in the study group spent more than 58 minutes outside per day. The people who received the least light were exposed to direct sunlight for only 13 minutes a day. The average exposure for 12 hours of the day was less than 100 lux (lux is a measurement of light intensity). By comparison, sunlight outdoors on a sunny day can be up to 100,000 lux – 1,000 times as much as in a dimly lit home or office. He identified that in a significant number of adults this could lead to a form of non-seasonal depression with symptoms similar to Seasonal Affective Disorder eg lethargy, low energy, carbohydrate craving, poor sleep patterns and depressed mood during the day.
Research into office lighting has shown that people experiencing positive emotional states tend to be more productive and that positive emotional states can be reinforced by providing people with their preferred work environment. Since daylight is almost universally preferred to electric lighting, it is likely that increased use of daylight will support workplace productivity.
The role of Bright Light Therapy
Professor Kripke notes that the treatment of depression with bright light is well established. Indeed, research published in May 2006 confirmed that Light Therapy is as effective as fluoxetine (Prozac™) in the treatment of depression. Light therapy showed earlier response onset and a lower rate of some adverse events relative to fluoxetine but there were no other significant differences in outcome between light therapy and antidepressant medication.
Kripke also highlights how bright light can help advance the sleep phase for those whose lives are out of phase with their body clock.
Where health and safety issues are paramount, for example amongst night workers and shift workers in manufacturing and the emergency services, there is a growing awareness of the need to keep workers alert and to help them manage their sleep patterns. Research continues to confirm the benefits of bright light therapy.
New research just published in the New Scientist suggests that social jetlag has major implications on smoking habits and that light therapy could help those wanting to quit. It could also explain why so many teenagers start smoking.
The role of light therapy is well-tested in the context of shift work and jet lag.
Shift work and irregular work patterns
Fatigue among shift workers is an internationally recognized problem across multiple industries. Night workers are just as likely as day workers to perform tasks requiring attention to detail, reasoning, decision-making, and other mental skills. Many night workers, such as the emergency and medical professions, media personnel and currency brokers, no longer fit the typical stereotype of the manual shift worker. Just about anyone who works long or irregular hours can be considered at risk.
A night worker, even one who has slept reasonably well, is no more alert between 2am and 8am than a day worker who has slept only 4 hours per night, 2 nights in a row. The cost of mistakes made by fatigued workers, including lost production, missed days from work, and medical costs, exceeds an estimated $100 billion annually in North America alone.
Typical indicators of fatigue include wandering and disconnected thoughts, headaches or stomach aches, drowsiness during shift and inability to sleep after shift, inattention to minor but potentially important details, degraded mental abilities (including memory, decision-making, and perception) and increased distractibility and irritability.
Unfortunately, the circadian rhythms of shift workers do not usually phase shift to adapt to working at night and sleeping during the day. This misalignment results in a multitude of negative symptoms including poor performance and reduced alertness during night work and poor daytime sleep at home. Sleep Medicine Reviews 6(5), 407-20, Oct, 2002 and The New England Journal of Medicine (1990)
Research at Volvo published in 2001 noted that the effects of bright light seemed to be positive in shift work. Light treatment reduced sleepiness and suppressed melatonin at work, and sleep length after work was easier to maintain.
Clinical research now confirms that bright light, in specific wavelengths, can help shift the internal body clock and regulate sleep patterns when used for 30 to 40 minutes upon waking leaving the subject more alert, energetic, and, in turn, more productive.
Jet Lag
Jet lag, or dysrhythmia, occurs after east-west travel when the body clock is no longer synchronized with the new time zone. It can disrupt more than 50 physiological and psychological rhythms. It gets worse with age – particularly after age 50. Unaided, it takes the body one day per time zone to readjust. It may take 2 to 3 weeks to completely realign body clock rhythms following long haul flights and this can have a significant impact on the ability of long distance executives to make reasoned business judgements.
Until recently, jet lag was dismissed as merely an unpleasant side effect of air travel. New research suggests that it may also cause memory loss, shrinkage of parts of the brain and negative side effects on blood pressure. Clinical research conducted at NASA and elsewhere demonstrates that in only two days the body clock can be reset to the new time zone with properly timed exposure to sufficiently bright light in specific wavelengths. With proper use of light therapy energy, mood, concentration, and sleep patterns can all be reset to the new time zone in as little as 60 minutes.
The biological mechanism
Researchers from Imperial College London, Johns Hopkins University, USA and Brown University, USA have discovered that melanopsin, a recently identified protein, plays a key role in a completely new light detection system in the eye.
It had long been assumed that the rod and cone cells of the retina are responsible for all light detection. However, over the last few years research has led to the inescapable conclusion that there is a third light detection system that has lain undiscovered over more than 100 years of intensive research on the eye.
In an important breakthrough scientists from the UK and USA have provided a direct link between melanopsin and this system. Melanopsin is an opsin-like protein which is expressed in a small number of ganglion cells in the retina of the eye. The research team tested whether melanopsin is part of the new light detecting system by measuring light-induced pupillary constriction in genetically modified mice that lacked melanopsin. When the mice lacking melanopsin were exposed to low light, their pupillary response was the same as normal mice, but when they were exposed to bright light their pupil constriction was incomplete.
Dr Rob Lucas from Imperial College London at the Charing Cross Hospital comments: “Our results show that melanopsin is particularly important in the detection of bright light. This is important because we think that this new photoreceptor is responsible for telling our bodies that it is daytime – daylight is always bright light.
“Our research has led us to believe that, quite apart from regulating pupil size, the melanopsin photoreceptors may be responsible for a broad range of responses to light, including its ability to keep us awake and alert. It is also likely that these photoreceptors are responsible for resetting our internal body clocks to local time following a flight across time-zones.”
The discovery of melanopsin explains why the non-sighted still know when it is time to go to bed!
The discovery of melanopsin also links with earlier research published in the Journal of Pineal Research that shows that the suppression of melatonin is optimised when using light at two specific wavelengths. At wavelengths of 465nm in the blue spectrum the maximum suppression occurs. However, the efficiency of the system diminishes over time unless there is also green light at a wavelength of 540nm. Sunlight has peaks at both these wavelengths. Research in progress seems to confirm that the green wavelength is necessary to ‘recharge’ the receptor.
Technological developments in light therapy
Generally, light therapy units for the treatment of SAD are large, unwieldy light boxes containing a large number of fluorescent tubes or light bulbs to generate a high intensity full spectrum light – typically rated at 10-15,000 lux. These units use a considerable amount of energy and generate unnecessary heat. Current research indicates that much of the energy is wasted because melatonin suppression occurs most efficiently at a very specific wavelength found in bright sunlight and overall light intensity is of secondary importance.
They are impractical in a corporate environment.
Light technology has moved on considerably in the last few years and light emitting diodes (LEDs) have now become established in many areas of manufacture. For example, the rear light clusters of premium cars are now made up of LEDs that give a much more reliable, higher intensity, low maintenance light that consumers less power than traditional bulbs.
Uniquely, the LEDs in The Litebook® produce light with peaks in the effective wavelengths of 465 nm and 540nm which match the peak
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