A Gene That Controls When You Want to Eat (NPAS2)

NPAS2 (neuronal PAS domain protein 2) is one of the core genes responsible for coordinating our circadian rhythms: the times of day at which we wake, sleep, eat, and experience daily changes in blood pressure, body temperature, metabolism, and other functions [R].

Like other circadian genes, NPAS2 responds to the cycle of light and dark to make sure our bodies perform certain functions at the right time of day [R].

NPAS2 specifically plays a role in determining when we sleep and when we eat. Sleep is broadly determined by the light and dark cycle, while eating is a little more complicated and appears to be learned according to the timing of food availability. That is, NPAS2 recognizes what times of day food is available and promotes appetite at those times [R].

This gene is also involved in sending messages with the neurotransmitter GABA and in controlling anxiety responses [R].

NPAS2 helps coordinate the rhythms of waking, sleeping, eating, and other daily cycles. It plays a central role in determining when we sleep and when we eat.

It is a popular thought in diet culture that eating at night—right before going to bed, specifically—can cause you to gain weight to a greater extent than eating during the day. However, clinical studies have found no evidence that eating at night is, by itself, harmful for the general population [R].

Alternatively, multiple studies have found that extending the nightly fast—the time period at night when we don’t eat—can have significant and far-reaching health benefits. One study found that people with a longer nightly fast were found to regulate their blood sugar more effectively. Another found a link between longer nightly fasts and lower rates of breast cancer [R, R].

These findings gel with other studies that have found significant health benefits to only eating within a specific, restricted time window each day [R, R].

Does NPAS2 Control When We Eat?

One mouse study found an odd connection between NPAS2, food intake, and health outcomes. In this study, one group of mice was raised with a normal NPAS2 gene, while another group was raised with a deleted NPAS2 gene (and therefore did not express NPAS2). Because of this gene’s connection to the circadian rhythms of sleeping and eating, the researchers expected the mice without NPAS2 to have an irregular feeding pattern [R].

Instead, they observed that the mice without NPAS2 had very few differences in comparison to the normal NPAS2 mice in terms of timing of food intake. However, when both groups of mice had their food taken away overnight (thus preventing the mice from eating when it was dark), the mice without NPAS2 experienced drastic and unhealthy weight loss. The researchers found a similar result when the mice in both groups were only fed during a four-hour window at the same time each day [R].

The authors of the study concluded that NPAS2 may have been helping the mice adapt to changes in the timing of food availability. Low expression of NPAS2 may make it more difficult for the body to adapt to changes in eating schedules [R].

NPAS2 helps the body establish an eating schedule and adapt to the time of day at which food is typically available. Low NPAS2 may make it more difficult to adapt to changes in eating schedules.

Although the deletion of NPAS2 has been linked with disordered feeding in animals, researchers have yet to pin down a strong link between this gene and nighttime eating habits in humans. The evidence is sparse so far, but broadly speaking, low expression of NPAS2 appears to make it more difficult for the body to adapt to changes in eating schedules [R, R].

The ‘A’ allele at rs2305160 has been associated with less seasonal variation in body weight and appetite, among other factors. While unconfirmed, this lack of variation may point to lower expression of NPAS2 and less adaptability to changes in eating schedules [R, R, R].

SNP Summary and Table

NPAS2 rs2305160

• ‘G’ = Associated with more seasonal variation in eating habits; may be better at adapting to changes in eating schedules
• ‘A’ = Associated with less seasonal variation in eating habits; may be worse at adapting to changes in eating schedules
• About 35% of all people worldwide have at least one copy of the ‘A’ allele.
• The ‘A’ allele is more common in people of European (54%) and American (49%) descent and less common in people of African descent (12%).