
### Introduction {: .ui .center .aligned .header}

Have you ever wondered why certain people sleep more when compared to others? And why some
people enjoy working late into the night instead of working early morning? Do you want to know what
your innate sleep rhythm is? The answer lies in your genes.

**Why is sleep so important?** Good sleep is extremely vital for optimal health and is associated with
mood, hormone levels, and weight maintenance. Sleep has different stages of unconsciousness and is
necessary for consolidating information and for reinforcing memories. The body also undergoes a
renewal and rejuvenation procedure, wherein the daily wear and tear of muscles and tissues are set
right by repair enzymes. This makes adequate sleep critical to maintaining good health.

The amount of sleep required differs from one individual to another. Similar to characteristics like hair or
eye color, sleep characteristics may also be associated with genetics.

The genetic basis of sleep helps highlight certain factors that could affect the quality and quantity of
sleep. A considerable part of life is spent in this state, and lack of sleep or sleep disturbances have been
associated with harmful effects on health and performance.

The heritability of sleep has been studied extensively on monozygotic twins, as they share a similar
genetic make-up and have similar sleep patterns like sleep cycle periods, rapid eye movement (REM)
and sleep latency times.

+ Twin studies have shown that there is **50%** heritability in **diurnal preference**
+ Family studies have shown that there is **20 to 25%** heritability in **habitual bedtime**
+ Linkowski et al. have shown that there is **90%** heritability in the **REM** (Rapid eye movement)
density
+ Twin and genome-wide association studies have shown that there is **49% to 90%** heritability in
**sleep duration**

Apart from genetic factors, environmental, behavioral, and cultural factors influence how much and
when we sleep. People living in hot climates enjoy an afternoon nap to avoid stepping out during the hot
mid-day sun. Other factors that could influence the quality and quantity of sleep are medications.

Genes share a complex relationship with the environment, and understanding the effect of genetic
variants will help in tailoring the environment to optimize sleep. This genetic report will help in identifying
how your genetic variants are likely to influence your sleep pattern, sleep quality and your predisposition
for sleep-related conditions.

