From the Research
Idiopathic hypersomnia is diagnosed when a patient experiences excessive daytime sleepiness despite adequate or prolonged nighttime sleep, without another medical or psychiatric cause, and is characterized by a mean sleep latency of less than 8 minutes on the Multiple Sleep Latency Test (MSLT), and fewer than two sleep-onset REM periods during the MSLT, as supported by the most recent study 1. The diagnostic criteria for idiopathic hypersomnia include:
- Chronic excessive daytime sleepiness occurring for at least three months
- A mean sleep latency of less than 8 minutes on the Multiple Sleep Latency Test (MSLT)
- Fewer than two sleep-onset REM periods during the MSLT
- Prolonged nighttime sleep (more than 11 hours) or difficulty waking up with sleep inertia (sleep drunkenness) The diagnosis requires ruling out other causes of hypersomnia, such as:
- Insufficient sleep syndrome
- Narcolepsy
- Sleep apnea
- Circadian rhythm disorders
- Medication effects
- Psychiatric disorders Polysomnography is necessary to exclude other sleep disorders and should show normal or increased total sleep time with normal sleep architecture, as noted in 2 and 3. A thorough clinical history is essential, as patients often report unrefreshing naps, significant sleep inertia, and feeling constantly tired regardless of sleep duration, as discussed in 4 and 5. It is also important to quantify sleep duration and excessive daytime sleepiness using self-reported and objective measures in a controlled procedure to differentiate long sleepers, patients with hypersomnia, and patients with idiopathic hypersomnia, as suggested by 1.