Sleep difficulties one year following mild traumatic brain injury in a population-based study

Highlights

• Forty-one per cent of people had sleep difficulties 1 year following a mild brain injury.

• There is a link between sleep and other outcomes following brain injury.

• Sleep quality does not spontaneously recover in many cases after brain injury.

Abstract

Background

Sleep quality affects all aspects of daily functioning, and it is vital for facilitating recovery from illness and injury. Sleep commonly becomes disrupted following moderate to severe brain injury, yet little is known about the prevalence of sleep disruption over time and how it impacts on recovery following mild injury.

Methods

This was a longitudinal study of 346 adults who experienced a mild brain injury (aged ≥16 years) identified within a population-based incidence sample in New Zealand. The prevalence of sleep difficulties was assessed at baseline (within two weeks), one, six and 12 months, alongside other key outcomes.

Results

One year post injury, 41.4% of people were identified as having clinically significant sleep difficulties, with 21.0% at a level indicative of insomnia. Poor sleep quality at baseline was significantly predictive of poorer post-concussion symptoms, mood, community integration, and cognitive ability one year post injury. The prevalence of insomnia following mild traumatic brain injury (TBI) was more than three times the rate found in the general population. Of those completing a sleep assessment at six and 12 months, 44.9% of the sample showed improvements in sleep quality, 16.2% remained stable, and 38.9% worsened.

Conclusions

Screening for sleep difficulties should occur routinely following a mild brain injury to identify adults potentially at risk of poor recovery. Interventions to improve sleep are needed to facilitate recovery from injury, and to prevent persistent sleep difficulties emerging.

Introduction

Traumatic brain injury (TBI) is the leading cause of disability in young adults worldwide [1], and the personal, societal, and economic costs of sustaining a TBI are substantial [2], [3]. The effects of TBI are wide ranging and disabling, with symptoms persisting for many years after injury, even following a mild TBI [4], [5]. The most common symptoms following a mild TBI include memory difficulties, fatigue, and poor sleep [6]. In the general population, rates of sleep problems can vary considerably based on how sleep is measured. Based on the Diagnostic and Statistical Manual of Mental Disorder (DSM) criteria [7], around 6% of people experience insomnia, with 34.5% found to be classified as poor sleepers [8]. Within the general population, poor sleep has been associated with an increased risk of poor health [9], absenteeism from work, and increased risk of accidents [10], [11], [12]. Following a TBI, the effects of poor sleep can be even more profound, exacerbating symptoms and impeding the ability to perform well at work or engage in rehabilitation [13], [14], [15], [16], [17]. Indeed, following moderate and severe TBI, poor sleep has been found to be associated with lower mood and poorer functional status [15]. Yet, despite its impact, sleep is one of the least explored symptoms following a mild TBI [17]. Understanding the role of sleep in recovery from injury and its impact on other symptoms is important to informing treatment and improving patient outcomes [18].

Sleep difficulties can occur as a direct result of the injury (eg, due to biochemical changes post TBI and injury to areas of the brain responsible for sleep) or as a secondary consequence in response to increased fatigue, lower mood, and changes in lifestyle following injury [17], [18]. Current evidence suggests that the most common sleep difficulties experienced are falling asleep (sleep-onset latency), poorer sleep efficiency, longer sleep duration, increased used of napping [18], [19], and increased sleep disruptions [20]. Whilst some cases of poor sleep post TBI resolve spontaneously, evidence suggests that sleep difficulties can become persistent for several years after injury [17]. In moderate and severe TBI, increased age, reduced cognitive ability, and being female have been identified as predisposing risk factors of poor sleep [21], yet it remains unclear if these factors are also risk factors of poor sleep following mild TBI.

A meta-analysis of prevalence studies on sleep difficulties following TBI [22] revealed that 49% of people experience clinically significant sleep disturbance post TBI, with 25–29% experiencing a specific sleep disorder. Whilst previous evidence has highlighted that sleep is highly problematic following TBI, estimates of the number of people affected vary widely. Variations may be due to differences in clinical definitions of sleep difficulties and sleep disorders, severity of TBI included, follow-up time points studied, and sample sizes used [17], [22], [23], [24]. A further limitation of the evidence is that few studies have recruited participants who did not seek hospital treatment following injury. Non-identification of cases is particularly problematic when studying the prevalence of symptoms following mild TBI, as injuries may be overshadowed by other more obvious or severe injuries and/or people may not be aware of the need to seek medical treatment following a mild TBI [25]. Indeed, about 30% of cases seek treatment from community practitioners such as physiotherapists or general practitioners [26]; thus, findings from hospital-based studies may not be generalisable to the whole mild TBI population. This study aims to determine the prevalence of sleep difficulties in a population-based sample of adults who experienced mild TBI, and to identify their trajectory for recovery over the year following injury.