The first team in the UK to explore whether there is a link between night-time sleep disturbances and daytime physical and mental functioning in ME/CFS recently published a paper on their work in the open access journal PloSOne.
Lead investigator Zoe Gotts, from the Faculty of Health and Life Sciences at Northumbria University in Newcastle-upon-Tyne, now tells the ME Association more about the study.
FROM PlosOne, 9 JANUARY 2015.
The Association between Daytime Napping and Cognitive Functioning in Chronic Fatigue Syndrome
Zoe M. Gotts, * E-mail: firstname.lastname@example.org
Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom
Jason G. Ellis, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom
Vincent Deary, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom
Nicola Barclay, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom
Julia L. Newton, Institute of Cellular Medicine, Medical School, Newcastle University & Newcastle Hospitals NHS Foundation Trust and UK NIHR Biomedical Research Centre in Ageing, Newcastle-upon-Tyne, United Kingdom
ADDITIONAL COMMENTARY BY ZOE GOTTS
Nobody has specifically investigated the relationship between night-time sleep disturbances and daytime physical and mental functioning in CFS/ME. Given these are very common symptom complaints in this illness, we decided to look at sleeping patterns in people with CFS/ME and try to understand if these have any association with levels of daytime fatigue, sleepiness and cognitive functioning.
The study involved recruiting participants from the local clinical service where the CDC criteria are recommended*. Patients completed sleep diaries over 2 consecutive weeks, including measures of sleepiness and fatigue, and cognitive tasks. Analysis of patients’ sleep diaries enabled us to characterise a complete 24 hour sleep and wake pattern over 2 weeks, and we compared key sleep parameters with specific patient characteristics and results from the functional assessments.
We found that several sleep parameters (wake duration, sleep efficiency and onset latency ) were outside of the normal range. When comparing sleep variables with the functional assessments, we found that patients who spent longer napping in the afternoon also had more cognitive dysfunction, including higher levels of sleepiness during the day.
We also found that those patients with a shorter illness length and a longer duration of being wake during the night, had the most severe fatigue. These results suggest that disturbed sleep and napping for longer periods later in the day may have implications for fatigue severity, levels of sleepiness and performance on cognitive tests, in individuals with CFS/ME.
The study highlights how we should consider the potential implications of sleep management strategies (i.e. daytime napping) and the sleep disturbances people with CFS/ME often experience (i.e. long periods of wake at night), on other aspects of the illness.
In this case fatigue, daytime sleepiness and cognitive functioning.
However, it is important to note that whilst sleep is an important determinant, fatigue can be influenced by multiple factors. Also, the conclusions drawn from this study are based on associations and do not confirm any causal relationships. Sleep problems experienced by people with CFS/ME are not all the same, and not all patients utilise daytime sleep; whereas for some patients sleeping during the day is vital in being able to manage their condition.
Daytime sleep can be beneficial for some people if implemented correctly, for example, short naps taken earlier on in the day, can actually help maintain short-term alertness, without interfering with nighttime sleep. It is when sleep at night is disturbed that we need to begin to consider how best to utilise daytime management strategies, and these strategies should be considered on an individual basis.
This study adds to the growing area of sleep research in CFS/ME, which is beginning to examine more aspects of sleep disturbances experienced by patients, and their potential management.
The authors are researchers and clinicians from the Faculty of Health and Life Sciences, Northumbria University and the Newcastle Fatigue Research Centre, Institute of Cellular Medicine, Newcastle University.
Sleep diaries: “Patients recorded the times at which they retired to bed, identified time of lights out, the number and duration of nocturnal awakenings, time of morning awakening, the number, duration and timing of daytime naps, alcohol and caffeine consumption, and medication use.”
Sleep Efficiency (SE): “Percentage of time spent asleep from the amount of time spent in bed.”
Sleep Onset Latency (SOL): “Length of time from lights out to first episode of stage 2 sleep”
* Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A, Schluederberg A, Jones JF, Lloyd AR, Wessely S, Gantz NM, Holmes GP, Buchwald D, Abbey S, Rest J, Levy JA, Jolson H, Peterson DL, Vercoulen J, Tirelli U, Evengard B, Natelson BH, Steele L, Reyes M, Reeves WC. The Chronic Fatigue Syndrome: A Comprehensive approach to its definition and study. Ann Int Med. 1994;121:953-9.