Impacts of 24/7 Shiftwork on Operators

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A high level summary of the physiological effects on control room operators

Operators – this is for you:  According to the Bureau of Labor Statistics, nearly twenty four million Americans either work a night shift or rotate in and out of night shifts.  That’s a significant portion of the USA’s workforce being exposed to the physiological effects of night work and the metabolic impacts that come with it:

asleep at wheel, drowsy, asleep, driving

on-the-job fatigue and sleepiness, reduced cognitive performance, and interference with the body’s metabolic processes. If your Operators are asleep at the wheel, perhaps a conversation is in order; any of these symptoms can hamper steps to create better safety, productivity, and the decisive behavior desired by companies.

As noted by the research, these physical effects do not just occur after a few days or weeks, but rather creep up over prolonged periods of time.

Smith LaRock Architecture P.C. specializes in the design of facilities for the Process Control Industry. We integrate architectural design requirements with key human factors to create designs that support the control mission, protect the Users, and promote better safety and deeper HSE benefits.

At Smith LaRock Architecture, we are not doctors or healthcare workers. We are architects: designers of facilities that are intended to perform a specialized function for our Clients. As architects focused on the integration of key human factors with the design of facilities that house these shift work careers, we think it is important to communicate what we have learned within this niche to help our stakeholders.

We are often faced with recommending changes to the darkened environments of the status quo control room that have not evolved over the past twenty five years.

And let’s be clear: working in a darkened environment during the day shift offers little differentiation from these later evening/night shift body chemistry effects – the room conditions a darkened room creates have essentially the same effect on people.  It becomes another form of night work when the Operator is actually forcing his or her body to produce the same chemicals as on a night shift through the environment they set up, thereby making them susceptible to the same physiological and psychological stresses.

…Operators in these spaces must understand what is physically happening to them as they perform this job.

Here’s how the lighting & vigilance relationship works:  when light enters our eyes, it activates cells in the retina which sends signals from the optic nerve to the suprachiasmatic nucleus (the SCN, which is essentially the body’s clock, governing our circadian rhythms). Impulses are produced at the SCN when light is present, and one of these signals goes to the pineal gland causing the gland to keep the production of melatonin switched off.   So the simple connection between light levels and melatonin production is that melatonin stays off when the lights are brighter.

By working in a darkened room, melatonin is produced, and with the low light levels, the body’s core temperature reduces.  Melatonin level peaks about 4-6 hours later and then starts to drop off, creating a waking mechanism and the body slowly wakes up.

Architecturally, Smith LaRock’s lighting design is planned to mimic this timing via a control system, but we also inject a specific frequency (color temperature) of light and quantity (lux) to raise the body’s core temperature so the Operator does not experience the production of melatonin and subsequent drowsiness.   Typically, an Operator is not even aware the light is raising the core temperature or inhibiting the production of melatonin.

The other issue we see that causes a different reaction in the Operator is the contrast levels between a modern computer screen and the dark environment;  shifting one’s gaze between the light and dark areas only slightly causes the iris to dilate and contract just like with bright lights in a dark ceiling. The physical in and out of the iris as the eye tries to focus creates great eye strain throughout the day, another reason we want the brightness of the room to be equally distributed at about the 400- 600 lux range to minimize this pumping action. See SLA’s whitepaper about Control Room Lighting for more information on this issue.

Our bodies have evolved to incorporate this period of repose so the brain can effectively ‘cool down’ and recover from daily use.    For people needing to make split second decisions, simply resisting those urges isn’t enough. And without better knowledge or understanding, it’s very difficult to remain vigilant in a darkened space, so we often see symptomatic relief through the use of caffeine, sugar, or some other stimulant.operator asleep

Meanwhile, other hormones are also produced in the bodies that have additional counter-productive effects: cortisol, for one, is the ‘fight or flight’ drug and is key to our discussion here, although it isn’t the only hormone produced in this setting that has detrimental effects.

Outside the normal instances when cortisol is produced in the body (simple waking or exercising), cortisol is also introduced to the body when presented with a stressful situation. Events such as a control system alarms, or a Plant upset condition can cause that shot of cortisol from the adrenal glands being sent into the body, matched by a dose of epinephrine.  The epinephrine narrows the arteries and increases the heart rate, both of which force blood to pump harder and faster.

The cortisol promotes a fight-or-flight response, and will also reduce or prevent the body’s insulin production in an attempt to prevent glucose from being stored, favoring its immediate use as energy to move those large muscles into action.

Since a principal function of cortisol is to counteract the effect of insulin on the body, over time the cells can become insulin resistant.  Unfortunately, the body remains in an insulin-resistant state when cortisol levels are chronically elevated, and worse, having those alarm situations repeatedly happen keeps the cortisol levels elevated for long periods of time.

Eventually, the struggle from the pancreas trying to keep up with the high demand for insulin results in higher levels of glucose in the blood, but the cells cannot get the sugar they need so the cycle continues and eventually, the body gains weight and can become obese as the conditions persist. Cravings of high-calorie food are typical, and overeating can result from this condition.  Operators should perform a self-check, being very cognizant of their own eating habits while on-shift to make sure they aren’t exhibiting this metabolic syndrome.

Another of cortisol’s functions in the body is to reduce inflammation, which is good, but over time, this evolution also suppresses the immune system. The person can then develop chronic inflammation caused by the lifestyle factors such as poor diet and exposure to ongoing stress, which further helps keep cortisol levels elevated.

operatorsA person’s immune system, reacting to unchecked inflammation in the body can lead to many other health problems: increased susceptibility to colds and other illnesses; increased risk of cancer; the development of food allergies; and a variety of gastrointestinal issues leading eventually to the possibility of autoimmune disease.

It is Smith LaRock’s goal to help our stakeholders to recognize and understand the problems associated with darkened environments for both the Company (ROI, Safety, Situational Awareness, etc) and the Operator (better HSE, body chemistry, and reduced absenteeism).

Operators should get more sleep, practice cardio and relaxation exercises, and address psychological/emotional issues in a healthy manner.  Cortisol is a fascinating hormone that is important to nutrition science on many levels. Understanding the basic cause and effect science of it, including its behaviors and relationships to other biochemical components and resultant health is critical to Operators taking control of their personal health moving forward.

 Operators should perform a self-check, being cognizant of their own eating habits while on-shift to make sure they aren’t exhibiting this metabolic syndrome.

power utility DOCGood design and good Operational acumen is the best approach to keeping cortisol levels down, vigilance up, and helping Operators master stress management and optimize diet.

We design the spaces to support better lighting, acoustics, HVAC, ergonomics, fit and finish in a manner that helps address the issues presented above so our Operators may perform their jobs with expectations of vigilance, improved  health, situational awareness and safety.

We recommend operator consoles that support better body postures, including both sit and stand positions, as well as designing locations for overview displays and view planes for both on-board and off-axis overview displays.  In our process to understand how we may better serve our Clients, we have found a great truth: in designing the right space we can offer health benefits to the Users: this serendipity helps reduce the potential for these health issues to emerge.

Our commitment to designing these functional control centers is that they meet both operational goals of the Company and the needs of Operators. See SLA’s ‘Lighting for 24/7 Control Rooms’ and other SLA whitepapers for additional information about this specialized design type and how SLA can assist you in your design needs, and please research this subject matter online for more information.

Written by:  Michael Smith – Smith LaRock Architecture Owner & Principal Architect


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