Shift Work Sleep Disorder

Shift work sleep disorder (SWSD) is a common sleep disorder characterised by disturbances in the sleep-wake cycle. It typically affects individuals who work non-traditional hours, such as night shifts or rotating shifts. It can significantly impact an individual’s physical and mental health, overall well-being and job performance.

SWSD is particularly common in night workers. Night-time workers are those who usually work in the evening or at night. According to the Office for National Statistics, 27% of the total workforce in the UK, equating to approximately 8.7 million people, were classed as night-time workers in 2022. With such a high proportion of the UK population working non-traditional hours, understanding the impact of SWSD is essential.

Understanding Shift Work Sleep Disorder

Shift work sleep disorder (SWSD) is a sleep disorder that primarily affects individuals who work non-traditional or irregular hours, such as:

• Night shifts
• Early morning shifts
• Rotating shifts
• Extended hours

SWSD occurs when there is a misalignment between an individual’s work schedule and their body’s natural circadian rhythm. The circadian rhythm is your body’s internal clock that regulates the sleep-wake cycle and other physiological processes, including your temperature, digestion, heart rate, blood pressure, hormones and brain activity. Your circadian rhythm corresponds with environmental cues, specifically daylight and darkness. When light enters your eyes, this signals your brain to synchronise your body’s internal clock with the external environment.

Light exposure during the day signals the body that it is time to be awake and alert. Conversely, darkness or decreased light exposure at night signals the body to prepare for sleep. The hormone melatonin plays a key role in regulating sleep-wake cycles. Melatonin levels typically rise in the evening as it gets dark, signalling the body to prepare for sleep. Melatonin levels decrease in the morning with exposure to light, signalling the body to wake up and be alert. If you work non-traditional shifts, these environmental cues do not align with your sleep-wake routine, which can result in difficulties sleeping during the day and being awake at night.

SWSD is considered a circadian rhythm sleep disorder because it results from changes to the body’s internal clock. When individuals work during hours that are typically designated for sleep, their circadian rhythm is disrupted, making it challenging for them to achieve restorative sleep. If your circadian rhythm is different to your sleep-wake cycle, this can make it difficult to sleep during the day and be awake during the night.

In individuals with SWSD, the demands of their work schedule disrupt their ability to get sufficient quality sleep. This can lead to symptoms such as difficulties falling asleep, difficulties staying asleep, excessive daytime sleepiness, fatigue, irritability and difficulties concentrating.

SWSD is prevalent among night shift workers and shift workers who do not consistently work night shifts (for example, they may work one week of night shifts and one week of day shifts). Industries that commonly employ night workers and shift workers include:

• Healthcare (e.g. doctors, nurses, paramedics and care workers).
• Emergency services (e.g. police officers and firefighters).
• Security work.
• Manufacturing.
• Transport (e.g. airline staff, train workers).
• Delivery drivers.
• Hospitality (e.g. bartenders and hotel staff).

Shift work sleep disorder can lead to an increased risk of accidents and injuries and decreased productivity. If left untreated, SWSD can have long-term physical and mental health consequences.

Causes and Risk Factors

Shift work sleep disorder has several primary causes. Understanding the causes and risk factors is essential to help shift workers implement effective prevention and management strategies that can help reduce the impact of shift work on sleep quality and overall health.

The main causes and risk factors of SWSD are:

Disruption of the circadian rhythm:

The primary cause of SWSD lies in the disruption of the body’s natural circadian rhythm. The circadian rhythm is a biological clock that regulates the sleep-wake cycle, hormone release, body temperature and other physiological processes over a roughly 24-hour period. This rhythm is primarily influenced by environmental cues, particularly light and darkness. When individuals work during hours when they would typically be asleep, such as during night shifts or rotating shifts, their circadian rhythm becomes out of sync with their work schedule, which can lead to difficulties in falling asleep, staying asleep and maintaining wakefulness during work hours.

Rotating shifts, irregular working hours and extended work periods:

Rotating shifts, irregular working hours and extended work periods are common features of jobs that contribute to SWSD. Rotating shifts involves working different shifts over a set period, such as switching between day, evening and night shifts. This constant shift in schedule disrupts the body’s internal clock, making it difficult for individuals to establish a consistent sleep-wake pattern. Irregular working hours, including night shifts or long hours, can also disrupt the body’s natural sleep patterns, leading to sleep deprivation and SWSD. Extended work periods, such as working overtime or consecutive long shifts, can exacerbate sleep disturbances and increase the risk of developing SWSD, due to insufficient time for rest and recovery.

Genetic or individual susceptibility factors:

While external factors, such as work schedules, play a significant role in the development of SWSD, there may also be genetic or individual susceptibility factors that contribute to the disorder. Some individuals may be inherently more sensitive to disruptions in their circadian rhythm or may have genetic variations that affect their ability to adapt to shift work schedules. Additionally, factors such as age, pre-existing sleep disorders, lifestyle habits and overall health can influence an individual’s susceptibility to SWSD. Further research is needed to fully understand the genetic and individual factors that contribute to SWSD and to develop personalised interventions for affected individuals.

Symptoms of SWSD

The symptoms of shift work sleep disorder can vary from person to person. The most common symptoms are:

• Insomnia, particularly difficulties falling asleep and difficulties staying asleep, including frequent awakenings or sleep interruptions and fragmented and non-restorative sleep.
• Excessive daytime sleepiness.
• Impaired alertness.
• Reduce cognitive function.
• Fatigue and a lack of energy.
• Irritability and mood swings.
• Headaches.
• Difficulties focusing, concentrating and making decisions.
• Decreased performance at work, including slower reaction times, reduced productivity and increased errors or accidents.
• Increased risk of accidents and injuries.

SWSD can have a significant impact on an individual’s overall well-being, job performance and long-term health. Some other ways SWSD can affect an individual’s life include:

• Decreased quality of life
  Persistent sleep disturbances and excessive daytime sleepiness can significantly reduce an individual’s quality of life and can affect their physical health, mental health and social relationships.
• Impaired job performance
  Sleepiness, fatigue and difficulties concentrating can impair job performance and lead to decreased productivity, increased absences and a higher risk of errors or accidents in the workplace.
• Strained relationships
  Mood disturbances, irritability and fatigue associated with SWSD can strain personal and professional relationships and lead to conflicts, stress and the breakdown of relationships.
• Alcohol or drug dependency
  Some people may begin misusing alcohol or drugs as a form of self-medication, to improve sleep or to cope with their symptoms.

Some of the long-term health risks associated with untreated SWSD are:

Cardiovascular disease

Chronic sleep disturbances are associated with an increased risk of cardiovascular disease, including:

• Hypertension
• Heart disease
• Stroke.

Metabolic disorders

Sleep deprivation and circadian disruptions may lead to metabolic disorders such as:

• Obesity
• Insulin resistance
• Type 2 diabetes

Mental health disorders

SWSD is linked to an increased risk of mental health disorders, including:

• Depression
• Anxiety
• Mood disorders

Weakened immune function

• Sleep plays an important role in immune function and chronic sleep deprivation associated with SWSD may weaken the immune system and increase susceptibility to infections and illnesses.

Diagnosis and Evaluation

Shift work sleep disorder is diagnosed through a comprehensive evaluation that considers your medical history, sleep habits, work schedule and symptoms. If you think you may be experiencing SWSD, it is recommended that you visit your GP. An important part of the diagnostic process is a sleep diary. Keeping a sleep diary can provide valuable information about your sleep-wake patterns over time. It can be beneficial to keep a record of information such as:

• Your bedtime (what time you fall asleep).
• Your wake time.
• Your sleep duration.
• Your working hours each day.
• Any factors that may affect sleep quality, such as caffeine intake or stress levels.

A sleep diary helps healthcare providers understand the consistency and quality of your sleep and may reveal patterns indicative of SWSD, such as disruptions related to shift work schedules.

Your GP may also ask you questions related to your sleep patterns, sleep quality and any symptoms you may be experiencing, such as difficulties falling asleep, excessive daytime sleepiness and impaired job performance. Your GP can assess the severity and impact of your symptoms to determine whether they meet the criteria for SWSD or another sleep disorder.

Once you receive a diagnosis, your doctor can then create a tailored treatment plan based on your specific needs and circumstances. Alongside treatment, you will likely also be offered regular follow-up appointments so that your doctor can monitor the progress of your treatment, make any necessary adjustments and address any new or persistent symptoms or concerns. Your GP can also help you with any coping strategies that can help you reduce your symptoms or overcome your sleep disorder.

Coping Strategies and Management

Alongside formal treatment options, there are some coping strategies you can implement to help you manage your sleep disorder. One of the most effective ways of managing SWSD is by improving your sleep hygiene. For example:

• Establish a bedtime routine
  Develop a calming bedtime routine to signal to your body that it’s time to wind down and prepare for sleep. This could include activities such as reading, taking a warm bath or listening to soothing music.
• Improve your sleep environment
  Making your bedroom a calm, relaxing and dark environment can help to improve your sleep. Using blackout blinds or curtains can limit how much daylight enters your bedroom. You should also ensure your bedroom is comfortable and a place you associate with sleep and relaxation. You should also keep your bedroom cool and comfortable for sleep by adjusting the thermostat or using fans, air conditioning or heating as needed.
• Limit screen time
  Minimise exposure to electronic devices, such as smartphones, tablets and computers, before bedtime, as the blue light emitted can interfere with melatonin production and disrupt sleep. Removing electronic devices from the bedroom is a good way to improve your sleep hygiene.
• Avoid heavy meals before bed
  Opt for lighter meals in the evening and avoid large meals or spicy foods close to bedtime, as they can cause discomfort and disrupt sleep.

Some other ways you can manage your SWSD are:

• Optimise your light exposure
  Exposure to bright light during waking hours, especially in the morning, can help regulate the circadian rhythm and promote wakefulness. Consider using bright light therapy or spending time outdoors during daylight hours.
• Limit noise disturbances
  It can be more difficult to sleep during the day because of outside noise. Even if your home is quiet, you may still be able to hear outside noise, such as traffic and people, particularly if you live in a non-rural area. Minimise noise disruptions during sleep by using earplugs, white noise machines or soundproofing measures to create a quiet sleep environment.
• Stay active during waking hours
  Regular physical activity can improve sleep quality and overall well-being. Incorporate exercise into your daily routine but avoid vigorous activity close to bedtime to help improve your sleep
• Practise relaxation techniques
  Incorporating relaxation techniques into your day-to-day life can help to improve your sleep. Some relaxation techniques you could choose include: Progressive muscle relaxation, Deep breathing, Meditation and mindfulness, Guided imagery, Autogenic training and Yoga.
• Regular exercise and a healthy diet
  Engaging in regular physical activity can improve sleep quality and overall well-being. Additionally, adopting a balanced diet rich in fruits, vegetables, lean proteins and whole grains can support overall health and promote better sleep quality. It is recommended that you avoid heavy meals, caffeine and alcohol close to bedtime.
• Melatonin supplements
  Melatonin supplements may be beneficial for some individuals with SWSD, particularly those who have difficulty falling asleep or adjusting to shift work schedules. However, use melatonin supplements under the guidance of a healthcare professional, as dosages and timing can vary depending on individual needs and circumstances. Melatonin supplements should only be used sparingly, rather than on a daily basis. This is to limit dependency or adverse effects.

Employer’s Role

Employers play an important role in supporting employees with shift work sleep disorder. Employers can raise awareness about SWSD and its impact on employees’ health and job performance through:

• Training sessions.
• Informational materials.
• Company-wide communication.

This helps reduce stigma and encourages employees to seek support if they are experiencing sleep disturbances.

Employers can also offer flexible scheduling options that allow employees with SWSD to have more control over their work hours and align them with their sleep needs. This may include allowing employees to choose preferred shifts, adjust start and end times or participate in shift-swapping arrangements with colleagues. Implementing thoughtful shift rotation policies can also help to minimise the disruption to employees’ circadian rhythms and promote better sleep quality. Employers can consider rotating shifts in a predictable pattern (e.g. clockwise rotation) to allow for adequate adjustment between shifts.

Providing designated rest areas or quiet spaces where employees can take short breaks or nap during work hours can help reduce fatigue and improve alertness, particularly for employees working long or overnight shifts.

Employers can review workload and job demands to ensure they are realistic and manageable for employees with SWSD. This may involve redistributing tasks, adjusting deadlines or providing additional support or resources to help employees cope with their workload more effectively. Some resources that employers can offer include:

• Employee assistance programmes.
• Counselling services.
• Access to sleep disorder clinics.

These resources can provide employees with additional support and guidance for managing SWSD and its associated challenges. Employers should maintain open lines of communication with employees to understand their needs, concerns and experiences related to SWSD. Regular check-ins and feedback sessions allow employers to address issues proactively and make necessary adjustments to support employees’ sleep and well-being.

Encouraging a culture of work-life balance promotes overall well-being and helps employees better manage the demands of shift work. This may involve promoting healthy lifestyle habits, providing opportunities for rest and relaxation and recognising the importance of downtime outside of work hours.

By implementing supportive policies, adjustments and resources, employers can create a work environment that promotes the health, safety and productivity of employees with SWSD, ultimately benefiting both the individual and the organisation as a whole.

Treatment Options

Once you have received a diagnosis of SWSD, your doctor can recommend treatment and create an individualised treatment plan. There are several different treatment options available, including:

Cognitive behavioural therapy for insomnia (CBT-I) 

SWSD shares many of the same symptoms as insomnia, so CBT-I can be an effective treatment option. CBT-I is a structured, evidence-based therapy aimed at addressing any maladaptive thoughts and behaviours that contribute to your sleep disturbances. Key components of CBT-I can include:

• Sleep restriction:
  Restricting time spent in bed to match the individual’s actual sleep duration to promote more efficient and consolidated sleep.
• Stimulus control:
  Establishing a strong association between the bed and sleep by limiting activities in bed. This helps break the association between the bed and wakefulness.
• Sleep hygiene education:
  Providing guidance on adopting healthy sleep habits, such as maintaining a consistent sleep schedule, creating a conducive sleep environment and avoiding stimulants close to bedtime.
• Relaxation techniques:
  Relaxation techniques, such as progressive muscle relaxation, deep breathing exercises or guided imagery, help individuals reduce physiological arousal and promote relaxation before bedtime, making it easier to fall asleep.

Sleep restriction therapy

This is another type of behavioural therapy that is used to treat sleep disorders. It aims to improve sleep efficiency by restricting the amount of time spent in bed to match your actual sleep duration. It involves a comprehensive assessment of your sleep patterns, including total sleep time, sleep onset latency (time taken to fall asleep) and the amount of time you spend awake during the night to establish your baseline sleep schedule.

The therapist calculates your average total sleep time and sets a specific bedtime and wake time, allowing for only the amount of time you typically sleep. For example, if you typically sleep for six hours per night, the therapist may restrict your time in bed to six and a half hours. The goal of SRT is to consolidate sleep by reducing time spent lying awake in bed. By restricting time in bed, your sleep drive strengthens and you become more likely to fall asleep quickly and stay asleep throughout the night. Throughout the therapy process, the therapist monitors your progress and adjusts the sleep schedule as needed based on improvements in sleep efficiency and subjective sleep quality.

Light Therapy

Light therapy involves exposure to bright artificial light, particularly in the morning, to help reset the body’s circadian rhythm and alleviate symptoms of SWSD. Light therapy may be particularly beneficial for individuals working night shifts or experiencing difficulties adjusting to shift work schedules.

Although not recommended on a long-term basis, medication, such as wake-promoting agents, may be recommended on a short-term basis. Stimulant medications may be prescribed to promote wakefulness and improve alertness during work hours. These medications are often used on a short-term basis to manage excessive daytime sleepiness associated with SWSD.

Medication

It is essential for individuals with SWSD to seek medical guidance for treatment, as healthcare professionals can provide personalised recommendations tailored to their specific needs and circumstances. Medical supervision is particularly important when considering pharmacological interventions, as medications may have potential side effects and interactions that require careful monitoring. Additionally, healthcare professionals can monitor treatment progress, adjust interventions as needed and provide ongoing support to help individuals effectively manage SWSD and improve sleep quality and overall well-being.