If there's anything that can put you into the sweetest trance of sleep, it would have to be the tender ride on your morning train commute.
Doesn't sound very pleasant, I know. However, when it comes to that quick 20-minute nap, it gets the job done.
The question is, however, how does your body know exactly when to awake in time to make it through those doors before they close?
Apparently, there happen to be a number of speculated reasons.
Your body knows your routine better than you'd think.
As long as you set a consistent schedule -- no matter what it is, be it an alarm or a train stop -- your body is awaiting a certain call time.
As long as you get off of your train around the same time every day, your brain can build an internal program to follow over time.
The technical term for your brain's clock is called the circadian rhythm. It's controlled by the suprachiasmatic nucleus, a cluster of nerves at the center of your brain.
The circadian rhythm is very sensitive to time, it and thrives on predictability.
That said, if you are getting off the train at the same time every day, you can count on your circadian rhythm to take note.
You're probably only in the first stage of your sleep during this time.
If you're squeezing in a quick snooze on the subway (anywhere from five to 20 minutes), your brain is only in a light snooze (stage one of sleep).
This means you're still able to hear what you need to hear around you. I like to call this part of the sleep cycle the “I'm Up” stage.
It's the very first stage of non-rapid-eye-movement (REM) sleep, in which your body is preparing to put you in a trance, but it's not quite there yet.
This means you can still hear and respond to things around you, especially if your surrounding sounds are important.
When the train conductor calls your stop, that is important, so your body awakes, you get off that train, and you go about your business.
But you might also wake up in time for your stop because your sleep schedule is generally off as it is.
You're probably not sleeping well in the first place.
Instead, like many commuters, you may be awaking at every stop or so, checking to see if it's yours. In this case, your body may be restarting non-REM sleep over and over again, which could be part of the reason why you rush out of the train so disheveled, and still feeling slightly groggy.
However, this is likely only the case if you aren't terribly sleep-deprived, and if you're not sleeping for over 20 minutes on the train.
If you're excruciatingly tired, or your subway snooze exceeds 20 minutes, then you're more than likely to ease out of non-REM sleep and into a deeper stage of sleep, which only makes it harder for you to wake up.
If you get into this deep sleep, you probably won't hear your stop.
That said, sleep wisely, and shoutout to the body's internal alarm clock for always making sure you're never late to work.