Narcolepsy, a type of sleep disorder, is characterized by severe and persistent daytime sleepiness, which may cause disruption in one’s daily routine. Although rare, the condition affects close to 70 people per 100,000 in the country. This article attempts to shed light on the types, causes, and diagnosis of narcolepsy.

Types of narcolepsy

• Narcolepsy type 1
  NT1 or Narcolepsy Type 1 is associated with cataplexy, a symptom that causes a sudden loss of muscle tone. This type of sleep disorder was referred to as narcolepsy with cataplexy. However, it is important to note that NT1 may not always cause cataplexy. It has been observed that those with narcolepsy have low levels of a chemical called hypocretin-1, which is required to control wakefulness.
• Narcolepsy type 2
  NT2 was previously referred to as narcolepsy without cataplexy. Those with this condition have normal levels of hypocretin-1. This type of narcolepsy could result from trauma to the brain or a tumor that may damage the hypothalamus, resulting in daytime weakness.

Causes of narcolepsy

• The root cause of narcolepsy is not known, but as mentioned above, one of its causes can be low levels of hypocretin -1, a chemical that regulates wakefulness. It has also been observed that those with narcolepsy type 1 have fewer hypocretin-making neurons.
• Additionally, researchers have also found that those with this condition carry a gene variation called DQB1*0602, which increases the risk of the disease. Since it’s genetic, chances of the sleep disorder being passed on from one generation to another remain high.
• Environmental factors, such as lack of ventilation and exposure to neurotoxins, may also increase the risk due to excessive immune responses and toxicity to brain cells.
• Apart from these causes, injuries to the brain, the presence of tumors, or damage to the hypothalamus may cause narcolepsy.

Diagnosis

• PSG
  A polysomnography test or PSG is performed when the patient is asleep. It is an overnight test that takes several measurements, including oxygen level, heart rate, breathing rate, and eye and leg movements. The test reveals how quickly the patient falls asleep and enters the REM state. The parameters help determine the type of narcolepsy by gauging sleep patterns and frequency of awakenings.
• MSLT
  Multiple Sleep Latency Test or MSLT diagnostic test is performed on the patient during the daytime. They are required to take five short naps, scheduled two hours apart. This helps in assessing how quickly they fall asleep and enter the REM state.