What is Narcolepsy?
Narcolepsy is a sleep disorder that is characterized by five symptoms:
1. Excessive daytime sleepiness
2. Cataplexy (sudden muscle weakness that occurs without any 'warning')
3. Sleep paralysis (a state of awareness with an inability to speak or move - usually occurs during waking up or falling asleep)
4. Hypnagogic hallucinations (vivid dreamlike experiences),
5. Disturbed nocturnal sleep
It affects approximately 1 in 2000 individuals and usually appears during childhood or early puberty.
There are two major types of narcolepsy:
Type 1 narcolepsy (NT1) : It is characterized by excessive daytime sleepiness as well as cataplexy. People with NT1 have lower levels of a brain hormone called hypocretin.
Type 2 narcolepsy (NT2) : Nt2 is a type of narcolepsy without cataplexy. People with NT2 have normal levels of hypocretin.
How Does Genetics Influence the Risk Of Narcolepsy?
The heritability among monozygotic twins for NT1 was found to be 20-30%.
If a first-degree family member has NT1, your risk for NT1 increases by 10-40 times. This shows that there are some genetic and environmental factors that play an important role in narcolepsy.
There are multiple genes that are associated with NT1, but almost all patients with NT1 carry a specific variant of the human leukocyte antigen (HLA).
HLA system regulates immune functioning in the body.
The currently identified genetic factors do not fully reveal the heritability of narcolepsy.
However, narcolepsy has been associated with a significant reduction in orexin producing neurons in the brain. Orexin is a neurotransmitter that is considered the master regulator of the sleep-wake cycle. A deficiency of orexin-producing neurons can cause narcolepsy.
P2RY11 and Narcolepsy
The P2RY11 gene is a member of the G-protein coupled receptors family, expressed by the immune cells. It plays an essential role in immune functioning and cell death regulation.
Variations in the P2RY11 gene might dysregulate the functioning of certain immune cells like CD8+T-cells and contribute to the development of narcolepsy.
rs2305795 And Narcolepsy
The rs2305795 is a G>A polymorphism located in the P2RY11 gene on chromosome 19.
A study documented that the rs2305795 A allele is associated with a reduced immune response to infectious triggers, thereby contributing to narcolepsy risk.
Non-genetic Influences On Narcolepsy Risk
Some risk factors for narcolepsy include:
- Autoimmune effects
- Upper airway infection
- Sarcoidosis
- Head injury
- Stroke
- Tumor
- Age (10-30 years)
Effects of Narcolepsy on Health
- People with narcolepsy find it harder to remember things and concentrate on doing an activity.
- There is a risk of depression and anxiety.
- Day to day activities like walking can become very dangerous when you fall asleep all of a sudden and lose muscle control.
- The sudden loss of muscle control can lead to weakness of arms and legs.
- People with narcolepsy may experience dream-like hallucinations, nightmares, and also paralysis when they sleep or wake up.
- It affects your sleep cycle and quality of sleep. REM sleep movements tend to occur at any time of the day in people suffering from narcolepsy.
TipsTo Manage Narcolepsy
There is no cure for narcolepsy, but certain lifestyle changes and treatments can help you manage it.
1. Try to stick to a sleep schedule, including short naps for about 20 minutes during the day.
2. Avoid alcohol, nicotine, and caffeine consumption, especially at night, and eat healthily.
3. Include some exercise in your daily routine to make you feel more awake during the day and tired at night.
4. Try to avoid activities that may be dangerous if you fall asleep suddenly, like driving or get enough sleep before you do that activity if necessary.
5. Talk to everyone you work with about your condition. They need to be informed so that they can help you if needed and know how to react.
6. Your doctor may prescribe stimulant medicines to help you stay awake during the day and antidepressants to help with the nightmares and hallucinations.
7. Counseling and support groups can help you relieve your emotions and deal better with the condition.
Summary
- Narcolepsy is a sleep disorder that usually appears during childhood or early puberty.
- There are two types of narcolepsy: NT1 and NT2. The symptoms of narcolepsy include disturbed nocturnal sleep, excessive daytime sleepiness, and a few others.
- Multiple genes are associated with NT1, but almost all patients carry a specific variant of the HLA gene that regulates immune functioning in the body.
- The P2RY11 gene, expressed in immune cells, plays a role in immune functioning and cell death regulation. The A allele of SNP rs2305795 is associated with a reduced immune response to infectious triggers, contributing to narcolepsy risk.
- Certain lifestyle changes like following a sleep schedule, taking short naps, exercising, reducing alcohol and nicotine consumption, and avoiding doing activities that may prove dangerous if you fall asleep suddenly can help manage narcolepsy.
- Certain stimulants and antidepressant medications can be taken under the guidance of a trained medical professional.
References:
https://pubmed.ncbi.nlm.nih.gov/30652006/
https://pubmed.ncbi.nlm.nih.gov/21170044/
https://pubmed.ncbi.nlm.nih.gov/24381371/
