Sleep restriction therapy for insomnia is associated with reduced objective total sleep time, increased daytime somnolence, and objectively impaired vigilance: implications for the clinical management of insomnia disorder.
OBJECTIVE
To investigate whether sleep restriction therapy (SRT) is associated with reduced objective total sleep time (TST), increased daytime somnolence, and impaired vigilance.


METHODS
Within-subject, noncontrolled treatment investigation.


METHODS
Sleep research laboratory.


METHODS
Sixteen patients [10 female, mean age = 47.1 (10.8) y] with well-defined psychophysiological insomnia (PI), reporting TST ≤ 6 h.


METHODS
Patients were treated with single-component SRT over a 4-w protocol, sleeping in the laboratory for 2 nights prior to treatment initiation and for 3 nights (SRT night 1, 8, 22) during the acute interventional phase. The psychomotor vigilance task (PVT) was completed at seven defined time points [day 0 (baseline), day 1,7,8,21,22 (acute treatment) and day 84 (3 mo)]. The Epworth Sleepiness Scale (ESS) was completed at baseline, w 1-4, and 3 mo.


RESULTS
Subjective sleep outcomes and global insomnia severity significantly improved before and after SRT. There was, however, a robust decrease in PSG-defined TST during acute implementation of SRT, by an average of 91 min on night 1, 78 min on night 8, and 69 min on night 22, relative to baseline (P < 0.001; effect size range = 1.60-1.80). During SRT, PVT lapses were significantly increased from baseline (at three of five assessment points, all P < 0.05; effect size range = 0.69-0.78), returning to baseline levels by 3 mo (P = 0.43). A similar pattern was observed for RT, with RTs slowing during acute treatment (at four of five assessment points, all P < 0.05; effect size range = 0.57-0.89) and returning to pretreatment levels at 3 mo (P = 0.78). ESS scores were increased at w 1, 2, and 3 (relative to baseline; all P < 0.05); by 3 mo, sleepiness had returned to baseline (normative) levels (P = 0.65).


CONCLUSIONS
For the first time we show that acute sleep restriction therapy is associated with reduced objective total sleep time, increased daytime sleepiness, and objective performance impairment. Our data have important implications for implementation guidelines around the safe and effective delivery of cognitive behavioral therapy for insomnia.
School of Psychological Sciences, University of Manchester, Manchester, UK.
Simon D
SD
Kyle
Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia.
Christopher B
CB
Miller
Institute of Brain, Behaviour and Mental Health, University of Manchester, Manchester, UK.
Zoe
Z
Rogers
School of Health and Social Care, University of Lincoln, Lincoln, UK.
A Niroshan
AN
Siriwardena
Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
Kenneth M
KM
Macmahon
Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, UK.
Colin A
CA
Espie
D001288:Attention / Q000502:physiology*; D015928:Cognitive Behavioral Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D012894:Sleep Stages / Q000502:physiology*; D013997:Time Factors; D016896:Treatment Outcome; D014851:Wakefulness / Q000502:physiology*
Adverse effects; CBT; insomnia; sleep restriction therapy; sleepiness; vigilance