The Revival of Active Behavioural Devices for Measuring Sleep Latency

Hannah Scott, Leon Lack
2017 SM Journal of Sleep Disorders  
Current Methods of Measuring Sleep Latency While PSG is an effective and accurate measure of what is understood to be sleep, there are many limitations of this method that make it impractical for use outside of the laboratory setting. PSG is resource-heavy and expensive because specialised equipment and trained individuals are needed to administer the procedure and score the data. Even though ambulatory PSG devices can be used in the home environment, the equipment and consumables are still
more » ... nsive and not readily available for use in many situations. Furthermore, in applications requiring instant knowledge of sleep onset, PSG recordings depending on subsequent analysis are of no use. Other automated simpler EEG based sleep systems that could provide instant assessment of sleep state are inaccurate in detecting Stage 1 sleep [1] . People having their sleep monitored via PSG are often inconvenienced by having to attend a sleep laboratory for setup for ambulatory monitoring, and people often experience discomfort while attempting to sleep with PSG, at least on the first night. These limitations are exacerbated when attempting to monitor sleep over multiple nights. Therefore, PSG is an impractical, often unavailable and unnecessarily cumbersome method for measuring sleep onset in many situations. Actigraphy is a common alternative used to monitor sleep in the home environment. These devices are inexpensive, convenient and widely-available, meaning that they are a practical method of measuring sleep. However, research-grade actigraphy devices are often inaccurate for estimating sleep onset [2, 3] . As for consumer actigraphy devices, many have no empirical evidence publicly available to support their validity [4], and those that do, consistently underestimate sleep latency [5, 6] . The underlying premise of actigraphy is that the cessation of limb movement is equivalent to the onset of sleep. However, people often cease activity long before they actually fall asleep, thus actigraphy devices often underestimate sleep latency [7] . The accuracy of actigraphy also varies considerably between individuals, and often underestimates sleep latency to a greater extent for sleep-disordered populations [8, 9] . Though they are practical measures of sleep, it is clear that actigraphy devices are unsuitable for situations which require the precise estimation of sleep latency. Active Behavioural Devices Out of practical necessity, researchers are beginning to re-investigate active behavioural devices for measuring sleep latency. Originally used to validate the scoring of 11] , these devices require responses to stimuli to measure sleep latency. Typically, auditory tones are emitted at regular intervals with users required to depress a micro-switch held in their hand in response to the auditory stimulus. If the device registers a response, it assumes that the user is awake, and when the user fails to respond to the stimuli (typically, to at least two consecutive stimuli), the device assumes that the user has fallen asleep by the first of the two missed stimuli. Thus, active behavioural devices operationalized sleep onset as the beginning of the sustained cessation of responses to stimuli.
doi:10.36876/smjsd.1015 fatcat:bgkoshb63zd6pesn2ctwlewwcq