Table 1.
The advantages and limitations of the various methods used to measure sleep
| Sleep measure | Measure | Advantages | Limitations |
|---|---|---|---|
| Polysomnography (PSG) | Objective | Accurate for determining multiple sleep parameters | Expensive |
| Gold standard | Can be used to diagnose sleep disorders | Experienced/trained technicians are needed to score the data | |
| Physiological | Can be combined with other physiological measures (hormone sampling under controlled conditions) | May not be able to capture usual sleep because of equipment and/or environment (first night effect) | |
| Determines sleep architecture (sleep stages and percentages of each stage) | Invasive/uncomfortable | ||
| Sleep architecture (stages 1, 2, 3 and REM sleep) | Measures brain activity as well as other physiological outcomes (muscle relaxation, eye movements respiratory effort and more) | Unsuitable for long-term sleep assessment; unless portable requires laboratory attendance | |
| Inter-/intraobserver variation | |||
| Actigraphy (wrist) | Objective estimate | Objective measure of sleep-wake timings | Cannot determine sleep architecture (sleep stages) |
| Can be used in the individual’s natural environment in free-living conditions | Provides an estimate of sleep-wake timings | ||
| Worn on wrist | Some devices have been validated for sleep duration against PSG | Some devices are not waterproof and will not capture information upon removal | |
| Based on movement | Ability to collect data over prolonged periods of time (up to 3 consecutive months) | Absence of physiological measures to determine sleep | |
| Cost-effective alternative to PSG | Requires concurrent sleep diary and minimum wear time | ||
| Noninvasive | May over estimate sleep during periods of inactivity | ||
| Multiple software and cut points for analysis | |||
| Actiheart | Objective estimate | Objective | Not validated against PSG for sleep |
| Additional physiological measures are obtained (heart rate) for sleep determination | Loss of signal if skin contact is poor or the ECG pads become loose/removed | ||
| Physiological | Can be used in free-living conditions and natural environments | Does not have the ability to determine sleep architecture (sleep staging) | |
| Can collect data over prolonged periods of time | Accurate accompanying sleep diary is usually required | ||
| Noninvasive | May overestimate sleep during periods of inactivity | ||
| Can be uncomfortable and/or result in skin irritation where ECG electrodes are placed | |||
| Expensive | |||
| Self-reported questionnaires | Subjective | Can be administered to large populations | Subject to a number of biases (recall, social desirability) |
| Quick/easy to administer | Variable response rates | ||
| Cost-effective | Subjective | ||
| Some are validated in different age groups to investigate different age-appropriate sleep problems (pain in the elderly, bedroom sharing in children) | Inaccurate for detecting sleep disorders | ||
| Less labor intensive compared to PSG | May be subject to missing data | ||
| Some are validated for sleep duration against objective measures of sleep | May result in time in bed being reported rather than total sleep time | ||
| Can help to ascertain information about multiple sleep parameters and other related factors | Information collected may not be accurate and some only ask one question | ||
| Parental questionnaire | Subjective | Inexpensive | Subjective |
| Administration is quick | Subject to a number of biases (recall, social desirability) | ||
| Immediate output | May have missing data | ||
| Permits data collection in large samples relating to pediatric sleep information | Likely to be inaccurate for older children and adolescents (parents may be unaware of night awakenings and/or other sleep features) | ||
| Less labor intensive compared to PSG | Variable response rates | ||
| May result in time in bed being reported rather than total sleep time, thus overestimating sleep causing inaccuracies | |||
| Sleep/time diary | Subjective | Obtains prospective sleep-wake data | Completion is tedious |
| Provides additional information about other sleep features (time in bed, sleep duration, night awakenings, napping, sleep quality) | Response rates may be low or diaries may be only partially completed (missing data) | ||
| Inexpensive | Subjective | ||
| Permits data collection in large samples | Labor intensive for the participant | ||
| Less labor intensive compared to PSG | Requires participants to be motivated to complete | ||
| Swift administration | Subject to inaccuracies/biases (recall, social desirability) |
REM rapid eye movement, PSG polysomnography