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1
Oblivious Beginnigs
A little snore emerges from the pile of bedding. You're fast asleep, and dreaming that you're lost in a busy city. You stop to cross the street and a car pulls up in front of you. The next thing you know, it becomes a truck backing toward you, making a reversing beep, beep, warning noise. You wait for it to stop and turn, thinking how familiar it sounds. Of course it sounds familiar, you realize--it's your father's truck that he uses to pick up the groceries. But he seems to be having trouble turning it, going forward, then backing up again. Finally he moves off, and you see that it wasn't a truck at all. Why would he use a truck for a box of cereal? It was a bicycle. You find yourself riding the bicycle with him, whizzing down a hill, the wind in your hair. There are lovely fields of flowers rushing by, faster and faster. You look down and see you're on roller skates. Surely this is a bit fast to be traveling on roller skates?
You groan and turn over, looking up at the ceiling. That was a weird dream, you begin to think, as it fades from your memory. You rub your eyes and look at the clock. You frown. The hands seem to be in the wrong places. You reach over and pick it up. That can't be right. Your watch, also on the bedside table, confirms that it is right. You're late! You've managed to sleep straight through the loudest alarm clock ever invented! But you're such a light sleeper--how could this possibly happen?
Sleep is not a simple activity. You may like to think of it as a bit of shut-eye or a little snooze, but your body and brain undergo some remarkable changes during sleep. If they didn't, you would literally lose your mind in a matter of days. We're all just 7 days from madness.
Going to sleep is not an on or off activity. We don't just "fall asleep" or "wake up"--it's actually much more complicated than that. We're also never "half asleep" as the common expression suggests, but we do slowly sink into different depths of sleep. These are called stages, and there are five different stages of sleep that we cycle through, several times every night.
When you settle down into bed and close your eyes, your first task is to move from wakefulness to stage 1 sleep. It's a gradual process in which your muscles relax, your brain slows down, and your eyes become more static. Your breathing becomes shallow and regular. If the electrical activity of your brain were being measured, we would see you moving from alpha waves to theta waves--your neurons are changing from a relaxed pulsing state to a slower, more synchronized state. But if you're disturbed during this stage, you probably won't even be aware that you'd been asleep. Stage 1 sleep lasts for 5 to 10 minutes, before you start to sink into stage 2.
Now your heart rate slows and your body temperature decreases. You may begin to snore, if you have a suitably floppy throat. Your muscles may occasionally twitch. Taking a look at the electrical activity of your brain, we would see spiky interruptions to your slow, pulsing theta waves, corresponding to those twitches. Your body is preparing for the deeper sleep of stages 3 and 4. Now your brain slows down even further, the neurons firing in relaxed pulses that become longer, slower delta waves. You're in stage 3 sleep and snoring at full volume. Stage 3 gradually becomes stage 4 when your brain produces the slower delta waves more than half of the time. This behavior of the brain is very different from the fast-changing, chaotic, and unsynchronized activity that takes place during wakefulness. Not surprisingly, you are the most disorientated when woken from a deep sleep.
Stage 4 is when sleep talking and sleepwalking occur. These behaviors have little to do with dreaming, because you are not yet dreaming. Movement and activity during deep sleep is driven more by primitive, instinctive emotions such as fear or anger. Astonishingly, people are capable of amazingly complex behavior while in this state. Those who suffer from severe sleep disorders may go to the kitchen and prepare and eat a meal, or, in more extreme cases, jump out of their bedroom window or drive a car. Somehow all the necessary parts of your brain are hijacked by this deeper, instinctive part of you, without your conscious mind ever waking up. Thankfully, severe sleep disorders are rare. Many of us may mumble a few words during deep sleep, but most of us are oblivious to the world, our brains in the most relaxed state possible.
The different stages of sleep each initially last around 10 minutes, and then go into reverse. After descending into the depths of stage 4, your brain then slowly wakes again, moving back to stage 3, then to stage 2. About 90 minutes after you first fall asleep your brain has almost risen back to wakefulness. But instead of moving to stage 1 and waking up, we move from stage 2 into a different kind of brain activity--dreaming. This is known as REM sleep (REM being an acronym for rapid eye movement). REM sleep is easy to detect, because the brain and body undergo profound changes. Your heart rate and breathing speed up, your body suddenly relaxes, and your eyes dart back and forth quickly behind your closed eyelids. Measuring your brain activity at this point would show your brain is closer to its state when awake, with a complicated mixture of asynchronous neuron firing. You are now in a dream world, though unaware, of course, that you are dreaming. You act out different roles in a virtual world made up by your own brain. Your moving eyes are following dream events as though they are real. To prevent your other muscles from doing the same, your brain has cut its own phone lines by blocking all messages from motor neurons to your major skeletal muscles. Your brain can no longer move any muscles except the ones controlling your eyes, and the involuntary muscles involved with your breathing and heart rate.
Dreaming is the best form of virtual reality there is. You genuinely believe you are experiencing the bizarre and often contradictory world unfolding around you. You may be exhilarated, saddened, angered, or even frightened by these experiences. They may be heavily influenced by very recent events in your waking life, or they may seem to have no clear relation to anything you've experienced. But they are all figments of your own imagination.
It may seem like a lost opportunity--each night we create entire worlds, memories, and experiences for ourselves, yet we have no control over them and little memory of them afterward. If only we could control our dreams, we would be gods of our own virtual universes every night, able to dream whatever we wanted. Fascinatingly, there is a technique known as lucid dreaming that makes this possible. It can only occur during REM sleep, and it usually happens when your conscious mind becomes aware that your virtual world just doesn't make sense. Perhaps you've pinched your nose and found you can still breathe through it, or you keep trying to read some text that changes every time you look at it. Or perhaps you realize that there are no such things as cartoon monsters in the real world. Whatever the trigger, when you realize you are asleep, your conscious mind is suddenly able to control the dream. More than 50 percent of us have had moments of lucidity during dreaming. Frequently the realization will simply make us wake up and the moment is lost. But with practice, we actually can hone our ability to control our own dreams. For some, this becomes such a fun experience that they use gadgets that will slightly disturb them during REM sleep.
Initially, dreaming lasts for only about 10 minutes. Then you may briefly wake up and turn over, or you may just sink back down through the stages of sleep again. This cycle of descending into deep sleep, then rising up to dream, then descending down again, will happen several times every night. In each cycle you spend less time in deep sleep and more time in REM sleep, until by the end of the night you may have had dreams that lasted as long as an hour. A typical person may have about five cycles of deep sleep and REM sleep every night. These cycles are heavily affected by age. Babies and young children spend much more time in REM sleep than adults do. As we get older, we also sleep less deeply, so adults spend less time in stages 4 and 5 and are more likely to enter REM sleep sooner and remain in it longer during the first sleep cycle.
We're still not sure why the brain sleeps the way it does. We don't know why we dream, and we don't know why we yo-yo between deeper and lighter stages of sleep every night. Perhaps it is an old evolutionary trick to make sure we are able to become alert to danger during the night. Perhaps it's a way to enable us to sort through the experiences of the previous day and better understand them. It seems likely that we're not the only ones who use this trick, though: most mammals and birds also sleep and dream like we do.
By the end of the night, most of us are spending little time in deep sleep and most of the time in REM sleep. It's why we often wake with a dream fresh in our minds--we have just stepped from our dreams into reality. It also means that should we hear any familiar noises that we've heard many times before, we are more likely to incorporate them into our dreams than to wake up. Even if we do briefly wake (and hit the snooze button), we're able to roll over and start dreaming again almost immediately because we're mostly in REM sleep by the morning.
Oversleeping often becomes a problem if you have not had enough sleep, if you're depressed, or if you haven't been sleeping normally. People who snore badly (enough to affect their breathing or enough for their partners to wake them), or who suffer from insomnia, may have interrupted sleep cycles, making them tired and irritable during the day. But if you are unfortunate enough to be deprived of all sleep (requiring constant and probably life-threatening disturbances to you), it only takes three days before you start to hallucinate and lose the ability to think normally. Prolonged lack of sleep also has a dramatic and serious effect on the immune system, to such an extent that you may die if you have no sleep at all for more than 11 days. But if you are an insomniac, don't worry. During those long hours that you may lie in bed, wishing for sleep, you will slip into stage 1 and 2 sleep regularly without being aware of it. It's enormously hard to stop someone from sleeping, just as it's enormously hard to stop someone from going to the toilet. There are some things we just have to do.
Ironically, waking up at the right time in the morning is a real problem for those who suffer from insomnia, but sleeping late happens to all of us now and again. Oversleeping is so common that there are a huge number of clever alarm clocks for sale. Some try to stop you from getting used to their alarms by making a different noise each day. Others actually jump off your bedside table while making the noise, forcing you to get out of bed and find them.
In the end, the best solution is to simply establish a good routine: Make sure you go to bed at a similar time each night and give yourself enough time to sleep (8 hours is recommended). Then, whether the alarm clock has gone off or not, you'll find you naturally wake up at the right time.
