Sleep feels so good, so of course it would make sense that it can be bad for you.

A new video from SciShow lists all the ways too little or too much sleep is linked to serious and potentially deadly medical conditions. Heart disease, stroke, diabetes, obesity and depression — research has shown a link between all of these problems and certain sleep levels. One study showed that twins who slept less than seven hours or more than nine hours were at a higher risk for depression, and another suggested people who got less than seven or more than eight were twice as likely to develop diabetes.

Read: Strange Things Your Body Does in its Sleep

We’ve known too little sleep is dangerous for a while — in fact, extreme sleep deprivation could eventually kill you. But there is not as much understanding about the effects of being in bed for too long every day, and while the general rule of thumb is to spend eight hours a night asleep, the jury is still out on the ideal amount. Different people also have different rhythms — we all know someone who claims to run just fine on five hours a night, while others often sleep into the afternoon.

If you are reluctant to give up your pillow time, you may not have to just yet. SciShow host Olivia Gordon concedes that while researchers have found links between different sleeping patterns and various diseases, it’s unclear whether the sleep contributes to the medical conditions, is a symptom of them or is somehow linked in an entirely different way. Right now the only place we fully understand sleep is in our dreams.

See also:

Hacks for Sleeping Through Noise

What Smartphones Do To Your Sleep