Actigraphy: Measuring Rem Sleep Accurately?

Actigraphy is a type of wearable sleep test that can be used to help diagnose certain sleep disorders and monitor the effectiveness of treatments. It is typically worn on the wrist or ankle and measures movement to determine sleep-wake patterns. While actigraphy can be used to measure total sleep time, sleep onset time, sleep efficiency, and wake time after sleep onset, it does not measure sleep directly and cannot be used to diagnose REM sleep.

Actigraphy's role in diagnosing sleep disorders

Actigraphy is a procedure that records and integrates the occurrence and degree of limb movement activity over time. It is a type of wearable sleep test that tracks your movements to analyse when you are asleep and when you are awake. An actigraph device looks similar to a wristwatch and is typically worn on the wrist or the ankle. Its basic components include an accelerometer that records movement, a data storage unit, and a programmable timing mechanism. The data collection process is usually performed over at least several days and often several weeks. Actigraphy is designed to provide minimal interference to day-to-day life, so you can go about your normal routine.

Actigraphy is used, sometimes in conjunction with additional tests, to help diagnose some sleep disorders and monitor the effectiveness of treatments. Examples of how actigraphy is used include:

• Insomnia: Actigraphy can be used to monitor sleep-wake patterns before and during sleep.
• Circadian rhythm sleep-wake disorders: Actigraphy can be used to monitor sleep cycles over multiple days.
• Sleep-related breathing disorders: Actigraphy can be used to track how long you are asleep as part of a home sleep apnea test.
• Excessive daytime sleepiness: Actigraphy can be used to track how long you normally sleep before doing a Multiple Sleep Latency Test.
• Insufficient sleep syndrome: Actigraphy can be used to track how long you normally sleep.

Actigraphy should not be used to diagnose periodic limb movement disorder.

Actigraphy's advantages and disadvantages

Advantages of Actigraphy:

• Actigraphy is a non-invasive method of monitoring human rest/activity cycles.
• It is a simple, affordable, and objective method of measuring sleep parameters and sleep quality.
• It is easy to complete for most people and simple to interpret, even for non-medical professionals.
• It is minimally invasive and can be worn for multiple days or weeks, providing a broad overview of sleep patterns.
• It is more accurate than a sleep log and can be used to monitor treatment progress.
• It is useful for measuring nighttime awakenings in children and can be used to diagnose circadian rhythm sleep-wake disorders.
• It is useful for assessing daytime sleepiness in place of a laboratory sleep latency test.
• It can be used to clinically evaluate insomnia, circadian rhythm sleep disorders, and excessive sleepiness.
• It can be used to assess the effectiveness of pharmacologic, behavioural, phototherapeutic, or chronotherapeutic treatments for sleep disorders.
• It is more affordable than polysomnography and can be worn during daily activities, making it more convenient and providing more generally applicable data.
• It is useful for determining chronotypes, sleep onset latency, total sleep duration, sleep consolidation, time spent in bed, movements, and the sleep cycle.
• It has been actively used in sleep-related studies since the early 1990s.
• It is especially adapted to paediatric and elderly patients.
• It is useful for determining the amount of wake-time activity and possibly estimating the number of calories burned.

Disadvantages of Actigraphy:

• Actigraphy is not a substitute for polysomnography, which is considered the 'gold standard' for sleep assessment.
• It does not measure sleep stages, brain activity (EEG), eye movements (EOG), muscle activity (EMG), or heart rhythm (ECG).
• It may not be covered by insurance.
• It may overestimate sleep in certain patient groups, such as those with insomnia, and has limited validity in estimating sleep-onset latency and daytime sleeping.
• It is less accurate for people with limited mobility and may not be suitable for those with skin sensitivities.
• It must be worn all day and all night, which can be inconvenient and may affect compliance.
• It may not be suitable for those with skin sensitivities.
• It is prone to technological malfunctions.
• It may not be suitable for those with skin sensitivities.
• It may not accurately detect wakefulness, especially in patients with disturbed sleep.
• It may not be suitable for those with cognitive impairments or those who are unable to self-report reliably.

Actigraphy's accuracy in measuring sleep

Actigraphy is a type of wearable sleep test that tracks your movements to determine when you are asleep and when you are awake. It can help doctors diagnose certain sleep disorders and monitor the treatment progress of people who have already been diagnosed with a disorder. The device looks similar to a wristwatch and is typically worn on the wrist or the ankle. It has an accelerometer that records movement, a data storage unit, and a programmable timing mechanism.

Actigraphy is designed to provide minimal interference to day-to-day life, so you can go about your normal routine while wearing the device. The data collection process is usually performed over several days or weeks. Actigraphy attempts to calculate sleep parameters such as the time you fall asleep, the time you wake up, how long you take to fall asleep, how long you sleep in total, and how much time you spend awake during the night after having fallen asleep. These parameters help medical professionals identify any peculiarities in your sleep schedule.

Actigraphy is generally considered more accurate than a sleep log but less accurate than polysomnography, an overnight test that measures electrical brain activity and other biological parameters. Actigraphy is quite accurate at identifying how long healthy people sleep but less accurate when evaluating fragmented sleep, reduced sleep time, long periods of trying to fall asleep, or restless sleep. It may overestimate sleep for some people and is less accurate for those with limited mobility.

The American Academy of Sleep Medicine acknowledges the potential benefits of using actigraphy for people with insomnia, circadian rhythm sleep-wake disorders, sleep apnea, insufficient sleep syndrome, and excessive sleepiness. Actigraphy may also be useful for monitoring treatment progress in people with insufficient sleep syndrome and sleep disorders in children.

While actigraphy may not provide the most detailed information, it offers a broad overview and is easy to use.

Actigraphy's limitations

Actigraphy is a non-invasive method of monitoring human sleep/wake cycles. It is a useful tool for diagnosing and treating sleep disorders, but it has some limitations.

Firstly, actigraphy cannot be used as a substitute for polysomnography, which is considered the 'gold standard' for sleep assessment. Polysomnography measures brain activity (EEG), eye movements (EOG), muscle activity (EMG), and heart rhythm (ECG), whereas actigraphy only measures movement. Therefore, actigraphy is not suitable for diagnosing sleep disorders that do not involve changes in movement, such as periodic limb movement disorder.

Secondly, actigraphy may not be accurate for people with limited mobility, as it relies on interpreting movements to determine sleep patterns. It may also overestimate sleep in certain patient groups, such as those with insomnia, as it infers sleep from a lack of movement. This means that people who are awake but lying still may be incorrectly classified as asleep.

Thirdly, actigraphy data can be affected by technical malfunctions or user error. For example, the actigraphy device may not properly record sleep during a nap or shower, or it may record periods of inactivity as sleep. Additionally, the user must wear the device consistently for it to be effective, which can be inconvenient and uncomfortable.

Finally, actigraphy may not be covered by insurance, and it is more expensive than a sleep diary, which is a simpler and more affordable way to track sleep habits.

Actigraphy's use in conjunction with other tests

Actigraphy is a non-invasive test that can be used in conjunction with other tests to help determine whether certain sleep disorders exist. It can be used in combination with a sleep log or an overnight sleep test.

Actigraphy can be used in conjunction with a Multiple Sleep Latency Test (MSLT) to diagnose excessive sleepiness. Patients with disorders of excessive daytime sleepiness may be investigated using an MSLT to help characterise the severity of daytime sleepiness or to identify the early onset of REM sleep during the day. Actigraphy is used to document sleep habits in the two weeks prior to the MSLT.

Actigraphy can also be used in conjunction with a home sleep apnea test to track how long a patient is asleep. Actigraphy can provide information about the total sleep time so doctors can understand what proportion of sleep time is occupied by lapses in breathing.

Actigraphy can be used alongside a sleep log to establish total sleep time and identify how long it takes a person with insomnia to fall asleep on average, over a period of several weeks.

Actigraphy can be used to evaluate treatment outcomes in patients with circadian rhythm sleep-wake disorders.

Frequently asked questions