My body clock cannot keep up

Mr V is a 36-year-old news editor who works for a 24-hour news TV station. He was referred to the sleep clinic by his employer’s occupational health department after he started falling asleep at work. He worked a shift pattern that involved one of three shifts: 8.00 a.m. to 4.00 p.m. (early shift), 2.00 p.m. to 10.00 p.m. (late shift) and 9.00 p.m. to 9.00 a.m. (night shift). He had been working in his post for seven years and initially had performed very well, rapidly advancing to a more senior position. However, approximately a year before his presentation he started to have difficulty concentrating during night shifts. He made a number of uncharacteristic mistakes which led his managers to express their concern about his performance and it was agreed that they would monitor his work more closely. It was during this monitoring period that he was found asleep at his desk on three separate occasions. Mr V admitted that he was finding night shifts increasingly difficult, primarily because he was unable to sleep during the day between shifts. This had never been a problem before, but he was now struggling to get adequate sleep, which left him feeling fatigued and sleepy at night.

He was referred to occupational health who initially wondered if he was depressed, but a psychiatric consult found no evidence of a mood disorder, though they commented that he had an anxious disposition. The matter escalated when he started to have difficulty sleeping at night as well, leading to daytime fatigue. When he was found asleep at his desk twice during day shifts he was advised to take a month’s leave and ‘sort himself out’. Mr V decided the stress of his job was getting to him and so went to visit his parents in France for the month. He noticed that his sleep improved fairly quickly and he was able to sleep well at night and feel alert during the day. On returning to work he went on to day shifts for two weeks and his sleep remained good. He was therefore confident that the problem had been resolved. However, when he rotated on to night shifts he had trouble sleeping during the day again and, even when he rotated back to day shifts, his sleep remained poor. Within a month he was falling asleep at work again and was suspended from his job.

Questions

1 What is the likely diagnosis?

2 Can you design shift patterns to minimize the risk of shift work disorder (SWD)?

3 How would you treat Mr V’s SWD?

Answers

1. What is the likely diagnosis?

SWD, a disorder which may affect over one-fifth of night workers and workers on rotating shifts. This is a circadian rhythm disorder leading to insomnia and/or excessive sleepiness, particularly during work shifts, leading to occupational or other dysfunction.

Humans have an internal circadian clock which is one of the major determinants of when we feel awake and when we feel sleepy. As diurnal creatures we are naturally predisposed to sleep at night and be awake during the day. This obviously makes it difficult to work nights, and most night workers will report periods of intense sleepiness and fatigue during night shifts that do not occur during the day. In addition to the difficulty of working at a time when the body expects to be asleep, it is also difficult to sleep at a time when the body expects to be awake. Therefore, despite being tired from a night shift (which is often longer than the day shift, as was the case for Mr V, and most doctors), the person may find it very difficult to go to sleep when they get home from work. Another complication is that when the worker is going home they may be exposed to bright morning light, which may have an alerting effect on the person and potentially confuse the body clock further.

Finally, it is often more difficult to sleep during the day than during the night. There is usually more light and noise during the day, which is likely to disrupt their sleep. There are also social factors such as the fact that they may need to sacrifice some of their sleep time to make phone calls to companies that are only open during the day, go to the bank, fetch the kids from school, etc.

Night work presents enough difficulties of its own. But when the person works rotating shifts an additional layer of complexity is added. Not only does the person have to cope with working unsociable hours, but these hours keep changing, usually at a pace too fast for the body clock to keep up. As a result, they may also find that they are sleepy at work when working day shifts and have difficulty sleeping at night.

SWD is not only problematic for the patient, but can have serious consequences for society as a whole. For example, pilots, truck drivers, doctors and nurses, police, air traffic controllers, train drivers and taxi drivers are all at high risk of SWD. As their alertness is adversely affected by the SWD it is concerning that it is so rarely recognized.

2. Can you design shift patterns to minimize the risk of SWD?

There is some controversy about which shift patterns are least likely to induce SWD. If the person does only a few days on each shift they will struggle to settle into the new schedule and, as soon as they do, they will rotate to a different schedule. On the one hand, doing a month of earlies, a month of lates and a month of nights gives the person’s circadian rhythm a sporting chance of catching up with the work schedule. However, a month of nights can be gruelling, particularly if their daytime sleep is disturbed by environmental stimuli, and has a significant impact on their social lives. Most jobs use fairly rapidly rotating shifts, spending a few days on each shift. There are three ways these shifts can be organized:

◆ Anti-clockwise rotation—the person works progressively earlier shifts, e.g. four days late, four days early, four days nights, four days off.

◆ Clockwise rotation—the person works progressively later shifts, e.g. four days early, four days late, four days nights, four days off.

◆ Random shifts where there is no clear pattern. This pattern is often found even when the rota uses one of the above patterns, as people swap shifts to meet social commitments.

As a rule, the clockwise rotation is the best shift pattern. As most people have an inherent circadian rhythm that is slightly longer than 24 hours, it is easier to delay your circadian rhythm to advance it. Therefore, it is easier to adjust to a progressive delay in the shift pattern. It also means that when you move from one shift to another you have a longer break between the shifts. For example, if Mr V moves clockwise from an early to a late shift, there is a 22-hour break between the end of the early shift and the start of the late shift. But if he moves from the late to the early shift there are only ten hours between shifts. This would give him less time to sleep between shifts, so he may start the early shifts sleep deprived!

3. How would you treat Mr V’s SWD?

There are four approaches to treating SWD: improving sleep between shifts, improving alertness during shifts, shifting the circadian rhythm to match the shift and designing the shift pattern to minimize the risk of SWD.

Improving sleep between shifts: The first interventions to put in place are the common sense things such as ensuring their environment is conducive to sleep, especially when they are sleeping during the day. This will often require the cooperation of their family. They should avoid caffeine for approximately six hours prior to the desired time of sleep onset. If their sleep is adversely affected by anxiety, then using cognitive behaviour therapy can be helpful. Some patients benefit from using hypnotics to establish their new sleep pattern when they change shifts and particularly when they are trying to sleep during the day.

Improving alertness during shifts: Timed naps are particularly helpful here. Naps can be timed to occur just prior to the start of the shift, in quiet periods during the shift and during periods when the circadian rhythm strongly predisposes one to sleepiness, e.g. at around 5.00 a.m. It should be noted that, as some people have an element of sleep inertia on waking from sleep, they should not nap if they may need to respond to emergencies immediately on waking. Judicious use of caffeine can be surprisingly effective and it can be used prior to the time they habitually feel sleepy to prevent the sleepiness occurring. Another possibility is to get exposure to bright light during the shift, as light has an alerting effect, and some patients find physical exercise to be helpful as well. In some cases stimulant medications such as modafinil are warranted and their use is supported by trial data.

Shifting the circadian rhythm to match the shift: This is often quite difficult, particularly in rapidly rotating shifts. As a rule of thumb, melatonin is given a few hours prior to the desired sleep period (though it should not be taken before driving home, as it is mildly sedative). Light exposure is timed to occur when the person first wakes up and they avoid light prior to going to bed (if necessary using dark glasses or welder’s glasses).

Mr V had already taken the common sense steps of ensuring his sleep environment was dark and quiet, and he unplugged his phone to ensure he was not disturbed while sleeping during the day. He tried using hypnotics to help him sleep between shifts, and while this improved his sleep it did not particularly improve his alertness, especially during night shifts. He was also anxious about using hypnotics in the long term. We noted that his shift pattern was fairly random and wrote to his employers asking them to consider putting Mr V on a clockwise rotating shift pattern. We also advised them to facilitate timed naps during work. They initially agreed to the clockwise rotating shift but this fell apart after a month, as it required significant changes to everyone else’s shifts and they were not willing to do this. They were not willing to facilitate planned naps, but said that all workers had a 45-minute break in the middle of their shift for ‘lunch’ and Mr V could use the bed in the first aid room to nap then instead of eating.

We gave Mr V melatonin 2 mg to be taken immediately on getting home from his shift and a light box to use immediately on waking. Although his shifts were too chaotic for us to have any realistic hope of shifting his circadian rhythm quickly enough to match his work pattern, we felt it was worth trying. He found the melatonin did improve his sleep and the light box had an alerting effect, so he started each shift feeling more awake than he had before. Mr V also used caffeine prior to the start of each shift and then again an hour prior to the times he felt most sleepy.

These interventions helped to a certain extent but he was still struggling, so our next step was to prescribe modafinil to help him stay awake during the shifts. This was initially very effective and he was coping much better at work. Unfortunately, after a few months he started to develop headaches from the modafinil and had to stop it. He was not keen on trying any other stimulants and had decided that he needed to change his lifestyle to fit his body clock, rather than the other way around. Therefore, with our support, he asked his employers to take him off night shifts permanently. They were not willing to do this unless he took a demotion and a significant cut in his salary.

After much soul-searching he decided his health was more important than the job and, with the help of his union, negotiated a severance package which he used to set himself up as a freelancer. He set himself very regular working hours and both his symptoms resolved completely. He was therefore discharged from the clinic.

Learning points

Shift work creates some unique problems for a person’s sleep–wake cycle. Some people cope with this well, but many will develop SWD.

Designing shift patterns to better match the workers’ circadian rhythms is a sensible intervention. In practice this means rotating the shifts clockwise, i.e. rotating to later shifts rather than earlier shifts.

Interventions involve improving sleep between shifts, improving alertness during shifts and shifting the circadian rhythm to better match the shift pattern.

Some patients will not improve despite the above interventions and therefore there are circumstances where the best treatment is to stop doing shift work.