ZZZzzz… huh? What?!… Sure you are feeling groggy with sleep, your mind is numb and your eyelids are drooping… and your messed-up bed looks so welcoming! Ah! At the moment, there is nothing better than dumping yourself onto it and sag into a lazy, monotonous spell of oblivion…
There you go…. Five minutes and you think you have entered a state of complete shut off, where your brain will have nothing to deal with for the next some hours…
But the truth is, sleep is anything but monotonous – it’s a roller-coaster ride in itself. So now that you have started your journey, your sleep would follow a pattern that is predictable and eventful, divided into a series of stages. Two broad stages of it are called NREM (non-rapid eye movement) and REM (rapid eye movement) and make up a 90 to 110 minutes cycle on average. Before entering REM, your NREM sleep would take you through different levels of brain activity.
Previously, as you lulled yourself into sleep, your brain waves began their transition from alpha waves (8-13 Hz, common during the awake period) to theta waves (4-7 Hz), your muscles relaxed and you started losing awareness of your environment.
Now as you enter stage 2 sleep, your brain may experience bursts of activity characterized by brain waves ranging from 11 to 16 Hz, known as the sleep spindles. If you notice, you have no consciousness of your environment any more.
Moving into stages 3 and 4, you are going to experience the deepest of your sleep. Your brain has now moved into a wave pattern that will increase in its amount of delta waves (0.5-2 Hz) with time. Meanwhile your heartbeat has come to a lowest rate and your muscles are receiving most of the blood flow. Wait… Felt that? Probably somebody tried to wake you up… well, people can be pretty difficult to wake up in this stage, so, even if somebody did try to wake you up right now, and you didn’t, it’s not your fault.
Around 70 minutes have passed since you dozed off… you should enter REM any moment now… There! Your eyes have started to move rapidly, your muscles are paralyzed, your brain waves have quickened, and you may have a dream or two here. Your brain is going to work actively in this phase, and will form neural connections and sort out the information you stashed into it all day long. If you lose out on REM, you are going to move into a phenomenon termed as sleep debt; meaning you’ll be requiring more sleep next time to cover up for the sleep you lost.
But it’s not over yet! The quicker brain waves that you acquired during REM are going to subside slowly and take you back to go through all the stages of sleep again, and again, and again… But in later cycles, the time of your REM will increase and your deep sleep will decrease, so that you will have the most vivid and memorable dreams around morning, and also making you easier to wake up. Oh, and another way to wake up easily next time you sleep, is to adjust your alarm clock to ring at a time that’s multiple of 90 minutes, because you are going to experience a state of brief awakening between two sleep cycles, and are more prone to waking up then, than in deep sleep.
… You peek at your cell phone to see the time; 9 hours gone. And you still feel like you can have another 9 hours… But normally, if you are fulfilling your sleep requirements, you should be well up, and feeling better… Is it your sleep lag? Oh well, a cup of coffee will do, but it’s a better idea to get your REMs before they get you…
-By Syeda Qudsia, NUST Center of Virology and Immunology.