What is Actigraphy?
Actigraphy is a non-invasive method used in sleep medicine to monitor human rest/activity cycles. An
actigraph device, typically worn on the wrist, records movement data over extended periods, often spanning several days to weeks. This data helps clinicians to assess sleep patterns, duration, and quality.
How Does Actigraphy Work?
An actigraph contains an
accelerometer, which detects motion through changes in acceleration. The collected data is then analyzed to differentiate between periods of sleep and wakefulness based on the frequency and intensity of movements. This method is particularly useful for tracking sleep in naturalistic settings outside of a
sleep lab.
Applications of Actigraphy in Sleep Medicine
Actigraphy is widely used for diagnosing and managing various sleep disorders, including:In addition, it is valuable for monitoring sleep patterns in populations such as children, the elderly, and patients with psychiatric conditions.
Advantages of Actigraphy
Actigraphy offers several benefits, including: Long-term Monitoring: Unlike polysomnography, which is typically conducted over one or two nights, actigraphy can continuously monitor sleep patterns over weeks or even months.
Non-Invasive: It does not disrupt normal sleep, providing a more accurate representation of typical sleep patterns.
Cost-Effective: It is generally less expensive than other sleep study methods.
Ease of Use: Patients can easily wear the device on their wrist, making it convenient for everyday use.
Limitations of Actigraphy
Despite its advantages, actigraphy has some limitations: Limited Specificity: It may not accurately differentiate between sleep and quiet wakefulness, potentially leading to overestimations of sleep duration.
Artifact Interference: Movements from activities like reading in bed or watching TV can be mistakenly recorded as wakefulness.
Less Detailed Data: It does not provide the comprehensive physiological data available from polysomnography, such as brain waves, heart rate, or respiratory patterns.
Comparison with Polysomnography
Polysomnography (PSG) is considered the
gold standard for sleep studies, providing detailed information on various physiological parameters. However, it is more intrusive and expensive. Actigraphy, while less detailed, offers a more accessible and less obtrusive option for long-term monitoring. In many cases, actigraphy is used as a complementary tool alongside PSG.
Conclusion
Actigraphy is a valuable tool in sleep medicine, offering a practical and cost-effective means of monitoring sleep patterns over extended periods. While it has some limitations, its non-invasive nature and ease of use make it an essential component in the assessment and management of sleep disorders. For comprehensive evaluations, actigraphy is often used in conjunction with other diagnostic tools such as polysomnography.
