If getting into bed at night is the best part of your day, I feel you. What happens next, though? Is it lights out in your brain as soon as you burrow underneath your blanket? If so, you might feel like falling asleep so quickly is a blessing—but what does it actually mean?

Your sleep onset latency (SOL), which is the amount of time it takes you to go from fully awake to being asleep, can depend on a lot of things. A major one is, obviously, how tired you are. It’s not a completely linear relationship, though. For instance, you might be exhausted but take forever to fall asleep due to insomnia and worrying that...you won’t get enough sleep. Vicious cycle.

Researchers are still trying to figure out the exact mechanism that switches you from wakefulness to sleep, so the relationship between SOL and sleep issues isn’t completely understood. Still, here’s what they do know so far.

First of all, you might not accurately remember how long it takes you to doze off.

Even if you’d bet your next paycheck on the fact that you conk out the moment your head hits the pillow, that might not actually be the case.

“We don't precisely recall the amount of time that it takes to fall asleep,” Brandon Peters, M.D., a board-certified neurologist and sleep medicine specialist, tells SELF. Research has shown that, in general, people can’t remember what happens in the minutes before they fall asleep, so you might not recall them at all. This is known as mesograde amnesia, and some researchers suggest it’s due to sleep spindles, or bursts of activity in your brain’s hippocampus as you’re transitioning from wakefulness to sleep. Your hippocampus helps you create and store new memories, so this tracks.

The only way to accurately measure the precise moment you fall asleep is by using an electroencephalogram (EEG) to monitor your brain activity. So, even if you’re convinced you catapult into dreamland the second you close your eyes, the process could take longer, Dr. Peters says.

If you do actually fall asleep in the blink of an eye, it doesn’t mean something’s inherently wrong with your health. Sometimes, though, it can be a sign you’re sleep-deprived.

There is nothing “technically abnormal” about falling asleep immediately, Andrew Varga, M.D., a doctor from the Mount Sinai Integrative Sleep Center who is board-certified in neurology and sleep medicine, tells SELF. “There’s no criteria for anything too short or instantaneous for falling asleep” at night, he says. Some people really are just blessed with being able to doze off as soon as they’re ready to sleep.

In fact, Dr. Varga says that sleep specialists typically worry about the opposite problem: “People that don’t have sleep issues should be falling asleep within 20 minutes.” If it frequently takes you longer than that, you could have insomnia.

However, there’s a huge caveat here. Let’s say you regularly aren’t getting the recommended seven to nine hours of sleep every night and you fall asleep instantaneously. You might be sleep-deprived. “If we don't get enough hours of sleep to meet our sleep needs, we will fall asleep faster,” Dr. Peters says.

Even if you think you’re chugging along just fine with five hours of sleep every night, falling asleep at the speed of light can signal that your body’s craving more rest.

If your habit of falling asleep really quickly extends to the daytime, that’s a clear sign you’re sleep-deprived or dealing with another health issue.

Don’t ignore a general tendency to nod off during the day. You might just need to shut your laptop a little earlier and actually go to sleep on time, or it could be something bigger. Health issues like sleep apnea and narcolepsy can also cause excessive daytime sleepiness, Dr. Peters says.