Ken Hume

The meaning of good sleep: a longitudinal study of polysomnography and subjective sleep quality

SUMMARY  The present study sought to investigate the meaning of subjectively good sleep, using a longitudinal and intraindividual design. Eight subjects slept in an isolation unit according to an irregular schedule of 6h sleeps and 1h naps, designed to give normal amounts of time in bed (1/3 of total), but variable sleep quality. Eight sleeps and eight naps were used for longitudinal simple and multiple regression analyses with standard polysomnographical sleep variables as predictors and subjective sleep quality as dependent variables. The results showed that subjective sleep quality (and related variables) was closely related to sleep efficiency, but not sleep stages. At least 87% efficiency was required for ratings of ‘rather good’ sleep. In addition, sleep quality ratings improved with closeness (of the awakening) to the circadian acrophase (17.00–21.00 hours) of the rectal temperature rhythm. The subjective ease of awakening differed from most other other variables in that it was related to low sleep efficiency. Objective and subjective homologues of sleep length and sleep latency showed high mean intraindividual correlations (r= 0.55 and 0.64, respectively). It was concluded that objective measures of sleep continuity were closely reflected in perceived sleep quality and that sleep quality essentially means sleep continuity.

The Subjective Meaning of Good Sleep, An Intraindividual Approach Using the Karolinska Sleep Diary

The present experiment used an intraindividual design to investigate the meaning and measurement of “good sleep.” Each of 16 subjects slept in an isolation unit according to a schedule (15 sleeps) designed to give variable quality of sleep. Self-rated sleep measures (from the Karolinska Sleep Diary) were obtained after each sleep and subjected to intraindividual regression analyses across time. Most subjective sleep measures showed a strong covariation across conditions. Subjective quality of sleep mainly involved variables of sleep continuity, in particular, perceived calmness of sleep and sleep efficiency. “Sleep quality,” “calm sleep,” “ease of falling asleep,” and ability to “sleep throughout” the time allotted strongly covaried and formed an index of sleep quality. Self-rated ease of awakening deviated from the general pattern and was associated with poor sleep quality. So was reported dreaming (related to awakenings). It was concluded that most subjective sleep measures tend to covary across conditions and that “good sleep” is mainly a question of sleep continuity.

Good sleep — its timing and physiological sleep characteristics

SUMMARY The present study used short sleep episodes to explore the relation between subjective sleep quality, timing and physiological content of sleep. Eight subjects participated in 18 4‐h sleep episodes to provide 4, 8, and 12 h of prior time awake before bedtimes at six different times of day in a sleep laboratory insulated from environmental disturbances. The results were analysed by ANOVAs and multiple regression techniques. Subjective sleep quality, calmness of sleep, ease of falling asleep, ability to ‘sleep through’, number of awakenings, and sleep latency showed a significant pattern of ‘better’ sleep with increasing prior time awake and with closeness to the circadian minimum (nadir) of rectal temperature (morning hours). ‘Ease of awakening’ in contrast, ‘decreased’ with increasing time awake and with closeness to the nadir/ morning hours. Multiple regression analysis showed that subjective sleep quality was predicted by subjective calmness of sleep and ease of falling asleep, among the subjective measures, and by total sleep time (TST) and slow‐wave sleep (SWS – stages 3 +4) among the physiological sleep measures. The subjective ease of awakening was predicted by slow‐wave sleep (negatively) and the circadian maximum of rectal temperature. The results indicate that the duration of wakefulness prior to sleep and the timing of sleep determine its physiological expression, which in turn determines its subjective impression.

Complaints caused by aircraft operations: an assessment of annoyance by noise level and time of day

The impact of aircraft movements on the local community surrounding an international airport was investigated using airport data on complaints, noise monitoring, aircraft flight paths and movements to assess annoyance due to noise level and time-of-day. As predicted, the louder the noise the more complaints were generated, with twice the complaints per movement at 110–114PNdB compared with 74–79PNdB.

Sleep disturbance due to noise: Current issues and future research

There is growing interest in carrying out further research to understand and reduce the impact of aircraft noise on airport neighborhood in anticipation of the projected substantial increase in global aviation. Soundscapes provide new analytical methods and a broader, more comprehensive appreciation of the aural environment, which may have a useful role in understanding noise-induced sleep disturbance and annoyance. Current noise metrics like Leq do not provide a common language to report noise environment to residents, which is a key obstacle to effective noise management and acceptance. Non-auditory effects complicate the production of consistent dose-response functions for aircraft noise affecting sleep and annoyance. There are various end-points that can be chosen to assess the degree of sleep disturbance, which has detracted from the clarity of results that has been communicated to wider audiences. The World Health Organization (WHO-Europe) has produced Night Noise Guidelines for Europe, which act as a clear guide for airports and planners to work towards. Methodological inadequacies and the need for simpler techniques to record sleep will be considered with the exciting potential to greatly increase cost-effective field data acquisition, which is needed for large scale epidemiological studies.

A new approach to investigate annoyance responses to sound elements

Soundscape research indicates that sound perception is a complex auditory experience with emotional content and the potential for annoyance should not be measured simply in terms of loudness. However, there are limited objective tools available to investigate annoyance and the relative health implications of negative soundscape elements. As part of a Positive Soundscapes (UK) project, the physiological responses [heart rate (HR), respiratory rate (RR) and electromyography (EMG) ] to soundscape elements were compared with the subjective assessment of pleasantness and arousal (assessed on 9 point scales) evoked in 80 subjects who listened to 18 x 8 second sound-clips. The data were analyzed via a linear mixed-model ANOVA. Listening to sound-clips lowered HR slightly but significantly. More unpleasant sound-clips caused larger falls in HR. Listening to a sound-clip raised RR slightly but significantly. The more pleasant the sound-clip was judged the greater was the rise in RR. The EMG tended to be raised by ...