(Published in Brain in 2015, by L Imbach and colleagues)
Written by Danielle Tiplady (Student Nurse, Kings College, London) & Lucia M Li
People who have had a traumatic brain injury (TBI) often report sleep disturbances, for example, they might need more sleep or feel excessively sleeping during the day. These disturbed sleeping patterns are thought to have a negative impact on their quality of life. The relationship between TBI and sleeping patterns is not clear. Furthermore, previous studies have not carefully examined the link between sleep problems and clinical measures, such as the chemical messengers in the brain during the first stages of treatment. In this study, the researchers studied the sleep-wake cycle after TBI. Along with this, specific clinical measures and laboratory results were also used, to see if they could predict which patients would develop sleep problems after TBI.
When patients were admitted into hospital, their injury severity was assessed according to the Glasgow Coma Scale and a CT scan of the brain helped to determine how bad and where the injury was. Patients also had various blood tests to look for disturbance in hormone levels and proteins that are associated with nerve injury. Patients then received usual medical treatment. Six months after their injury, patients had their sleep assessed using detailed questionnaires, by making sleep diaries and through actigraphy and polysomnography. An Actigraph is a device worn on the body, commonly the wrist, to measure how much a person moves, helping to understand their sleep patterns. Polysomnography is method of measuring brain waves, heart rate and eye movements during a sleep session at the research laboratory. These techniques are used to diagnose sleep disorders.
As well as looking at patients who had TBIs, a ‘control group’ made up of healthy volunteers who had never had a brain injury were also studied. A control group that is as similar to the 'study group' is useful to compare to the TBI patient group, as then researchers can be more confident that the differences that are seen between the groups are due to the brain injury and not because of other things.
140 patients were considered for recruitment into the study. However, many were excluded as they had existing neurological illnesses, had problems with drug or alcohol abuse or had a psychiatric illness, meaning it would be difficult to say that changes were solely due to their TBI. 60 patients were eligible for the study, but 18 people left the study within the 6 month period. 42 people completed the study, of which 31 patients had all the assessments.
This study found that, 6 months after a TBI, patients slept vastly more than the healthy volunteers. Daytime sleepiness was seen in 57% of TBI patients in comparison with 19% of the healthy subjects. Patients were also much more likely to wake up several times during their sleep than the healthy volunteers were. The biggest risk factor for developing sleep problems after brain injury was the presence of intracranial haemorrhage, a type of bleeding on the brain. Another risk factor was the severity of the injury – patients with more severe injuries were more likely to have sleep disturbances. The researchers also found that patients, but not healthy volunteers, underestimated how much sleep they needed and how sleepy they were during the day. This suggests that patients’ own reports of sleep problems may not be fully reliable, and future research studies could use objective assessments to measure sleep problems.
A big strength of this study is that a wide range of both subjective measures (judgements by the participants themselves) and objective measures (judgements made by people who could observe the participants) of sleep disturbances were used, which gives a fuller picture of this problem. Also, the researchers investigated the risk factors for post-injury sleep problems. A small issue is that some of the blood tests done may not have been precise enough to determine whether hormonal imbalances also affect sleep. A common problem with studies in brain injury is the dropout rate – in this study, almost 1 in 4 patients left the study. This could potentially cause bias in the results if the reason for dropping out is not known, for instance, if many patients had dropped out because they hadn’t recovered very well then this important group would not be represented in the study.
Nevertheless, this study was the first to use a comprehensive study of sleep problems after brain injury and provides some interesting questions for future research, as well as potential issues for doctors to be aware of when they look after brain injured patients.
Written by Danielle Tiplady (Student Nurse, Kings College, London) & Lucia M Li
People who have had a traumatic brain injury (TBI) often report sleep disturbances, for example, they might need more sleep or feel excessively sleeping during the day. These disturbed sleeping patterns are thought to have a negative impact on their quality of life. The relationship between TBI and sleeping patterns is not clear. Furthermore, previous studies have not carefully examined the link between sleep problems and clinical measures, such as the chemical messengers in the brain during the first stages of treatment. In this study, the researchers studied the sleep-wake cycle after TBI. Along with this, specific clinical measures and laboratory results were also used, to see if they could predict which patients would develop sleep problems after TBI.
When patients were admitted into hospital, their injury severity was assessed according to the Glasgow Coma Scale and a CT scan of the brain helped to determine how bad and where the injury was. Patients also had various blood tests to look for disturbance in hormone levels and proteins that are associated with nerve injury. Patients then received usual medical treatment. Six months after their injury, patients had their sleep assessed using detailed questionnaires, by making sleep diaries and through actigraphy and polysomnography. An Actigraph is a device worn on the body, commonly the wrist, to measure how much a person moves, helping to understand their sleep patterns. Polysomnography is method of measuring brain waves, heart rate and eye movements during a sleep session at the research laboratory. These techniques are used to diagnose sleep disorders.
As well as looking at patients who had TBIs, a ‘control group’ made up of healthy volunteers who had never had a brain injury were also studied. A control group that is as similar to the 'study group' is useful to compare to the TBI patient group, as then researchers can be more confident that the differences that are seen between the groups are due to the brain injury and not because of other things.
140 patients were considered for recruitment into the study. However, many were excluded as they had existing neurological illnesses, had problems with drug or alcohol abuse or had a psychiatric illness, meaning it would be difficult to say that changes were solely due to their TBI. 60 patients were eligible for the study, but 18 people left the study within the 6 month period. 42 people completed the study, of which 31 patients had all the assessments.
This study found that, 6 months after a TBI, patients slept vastly more than the healthy volunteers. Daytime sleepiness was seen in 57% of TBI patients in comparison with 19% of the healthy subjects. Patients were also much more likely to wake up several times during their sleep than the healthy volunteers were. The biggest risk factor for developing sleep problems after brain injury was the presence of intracranial haemorrhage, a type of bleeding on the brain. Another risk factor was the severity of the injury – patients with more severe injuries were more likely to have sleep disturbances. The researchers also found that patients, but not healthy volunteers, underestimated how much sleep they needed and how sleepy they were during the day. This suggests that patients’ own reports of sleep problems may not be fully reliable, and future research studies could use objective assessments to measure sleep problems.
A big strength of this study is that a wide range of both subjective measures (judgements by the participants themselves) and objective measures (judgements made by people who could observe the participants) of sleep disturbances were used, which gives a fuller picture of this problem. Also, the researchers investigated the risk factors for post-injury sleep problems. A small issue is that some of the blood tests done may not have been precise enough to determine whether hormonal imbalances also affect sleep. A common problem with studies in brain injury is the dropout rate – in this study, almost 1 in 4 patients left the study. This could potentially cause bias in the results if the reason for dropping out is not known, for instance, if many patients had dropped out because they hadn’t recovered very well then this important group would not be represented in the study.
Nevertheless, this study was the first to use a comprehensive study of sleep problems after brain injury and provides some interesting questions for future research, as well as potential issues for doctors to be aware of when they look after brain injured patients.