It’s the night before a big meeting at work—or a race you’ve been training months for—and you want to do everything you can to get the next day off to a great start. How much sleep do you need to be at your best?

For years, the magic number for a good night’s sleep has been eight hours. While this is a good general guideline, the real answer is more complicated, says Jacqueline Lane, PhD, a postdoctoral researcher studying the genetics of sleep at Massachusetts General Hospital.

Research has shown that the amount of sleep we need varies between individuals and can depend on activity level, Lane says. Relatives from the same family also tend to have similar sleep needs, suggesting sleep habits can be influenced by our genetics. There are some families who can get by on just six hours of sleep, while others will feel foggy and have trouble concentrating if they don’t get at least eight hours.

“Obviously, there is something about the biology [between these two groups] that is different. Can we look inside their genome and find that biological difference, and understand how it is influencing their ability to sleep less without the negative consequences?”

The Genetics of Sleep

Lane is hoping to identify the genes responsible for sleep by comparing the genomes of individuals with sleep disorders to those who sleep normally. She explains that 99.9% of human genomes are similar, and that the diversity between people all stems from the remaining 0.1%.

By looking for changes in this small portion of the genome that varies between people, Lane may be able to identify genetic clues that help to define our sleep needs and contribute to sleep disorders such as insomnia.

“If my genome is very different at one spot compared to yours, and I have sleep trouble—and everyone who has sleep trouble has the same difference that I do—then maybe that that spot relates to how we sleep.”

The genomic data for this study has been drawn from the 500,000 participants enrolled in the UK Biobank, who have provided DNA samples and answered questions about a variety of health-related topics, including their sleep patterns. Having such a vast array of data to analyze is “a real game changer,” Lane says.

Lane’s research so far has helped to identify the area of the genome that is associated with sleep, though more work has to be done to narrow down to specific genes, and to figure out how these genes work to affect sleep behaviors.

Health Implications of Sleep Disorders

While individual sleep needs may vary, sleep disorders such as insomnia are real and can have a significant impact on an individual’s health and quality of life, Lane says.

“We are finding that insomnia is clearly a disorder. People with insomnia have increased risk of psychiatric and metabolic disorders, and their overall life expectancy is shorter.”

If researchers are able to learn more about how the genetics of sleep impact the development of psychiatric and neurological disorders—and vice versa—they may be able to develop new prevention and treatment strategies that stem from improving sleep habits.

“People have known there is some link between psychiatric and sleep disorders, but the real question is determining the nature of that link,” Lane says. “If I can get somebody to go from sleeping six hours at night to eight hours, will that prevent them from developing depression or schizophrenia?”

Making Your Sleep Patterns Work for You

While it is not necessarily a bad thing to be genetically wired for less sleep than others, it can require some lifestyle adjustments, particularly if you live with others who need more sleep at night.

Lane recalls the story of one woman who only needed five hours of sleep each night. After the woman had children, she found that she was good at getting up and taking care of them at night because she did not need much sleep.

The woman then started fostering infants who were born to drug-addicted parents and needed a lot of attention and snuggling throughout the night.

 “I think this reminds us that sometimes we think about things as a disorder, but it is all about the way you look at it,” Lane says. “She sees it as a gift, and can use it that way.”