People who sleep longer are more suited to life on Mars than early risers. This claim has been reinforced after scientists found out that early risers may be unable to adjust to Mars’ day.

“The rotation speed of Mars may be within the limits of some people’s internal clock, but people with short running clocks, such as extreme morning types, are likely to face serious intractable long-term problems, and would perhaps be excluded from any plans NASA has to send humans to Mars,” Andrew Loudon said in a statement. “If we ever do get to the Red Planet, I suspect we will be faced with body clock problems; those people with abnormally slow body clocks would be best suited to living there.”

The study, published in the journal the Proceedings of National Academy of Sciences, is the first one to show how an internal body clock syncs with the Earth’s rotation speed. It involved observing how the proportion of animals with 24-hour or 20-hour clocks released into outdoor pens change in 14 months.

The mice with fast-running clocks gradually become less common in each generation so consequently, the mice with slow-running clocks or normal 24-hour clocks dominated the population. The results also have implications for health as previous studies show the association between developing type 2 diabetes and people who have abnormal body clocks due to working night-shifts.

So early risers, whose body clocks run faster, may struggle to adjust with the Red Planet’s slow rotation that makes one day 37 minutes longer than a day on Earth. Loudon adds that a correctly ticking body clock is essential for survival in the wild and this has evolved as a crucial component for life on Earth.

Early risers are not the only ones who will have a problem in Mars. NASA food scientist Vickie Kloeris told Popular Science that designing a menu for vegan, lactose-intolerant and gluten-intolerant astronauts or others with dietary restrictions would cost a lot of money so these people might as well stop dreaming of travelling to Mars.