Lately, I’ve been thinking about why I go to sleep in lectures so often. It isn’t because I’m tired, or because I’m bored; there are plenty of times when I am both tired and bored and fail to fall asleep with the kind of dependability that I do in lectures. Nor is it because I’m sitting still for an hour; I often sit, tired and bored, for several hours and again, I don’t fall asleep. The process of sleeping is admittedly accelerated by the lecture being in a dark and warm room, but then those conditions are neither necessary nor sufficient, and of course they accelerate any form of sleeping.
And contrary to popular belief, I don’t actively try to fall asleep in lectures. In fact, for most lectures I’m engaged in a mental struggle to stay awake. It’s not as I’m not making an effort here. So what is it that’s so unique about lectures that makes me fall asleep in them?
I think it’s divided attention. A lecture consists of auditory and visual stimuli, namely a lecturer talking and perhaps some slides, that reach my sense organs and are converted into information. During lectures, I try to attend to this outside stimuli, but for some reason, I usually can’t. Traditional psychologists would say that the reason behind this is because the stimuli isn’t salient enough to keep my attention from drifting off into introspection. Which basically means, I’m not paying attention because I find the lecture boring.
I don’t agree with that; I’ve been in many lectures whose topics I find highly interesting and important and I still manage to doze off, even if only for a few seconds. I think it has more to do with the presentation of the information; that is, the nature of the stimuli. I would venture that the distilled information bandwidth of most lectures is a constant low enough to be easily processed by most people, including me, consequently leaving a fair amount of spare processing power sloshing about doing nothing (I appreciate that it’s not particularly accurate to use a computer as a metaphor for the brain, especially in terms of the brain having a linear and generalised pool of processing power, but bear with me). This spare power might be used for any number of things, which could include further processing of the lecture information, processing of other non-lecture stimuli, or simple introspection.
For me, I believe that in a lecture I use a significant portion of my brain to attend to the lecture. The rest of my brain attends to something else, such as what I’m going to cook for dinner tonight, or how to design a new kind of streetlamp cover that would reduce light pollution. For most of the time, these two attentive streams can co-exist happily and independently without infringing on each others’ processing power. But when some event occurs that upsets this balance, my introspective stream can start gobbling up processing power from my lecture stream (without my conscious notice). At this point, I stop paying attention to the lecture, which means that I essentially can’t hear or see what’s in front of me, despite being awake*. From that point, it’s an easy hop, skip and jump to falling completely asleep, which I would compare to a sort of cascading, spiralling experience in which my neurones progressively succumb to whatever signals cause me to lose consciousness.
*Obviously I can still hear and see. But I’m not paying attention to those senses, which means that if you asked me what the lecturer had just said, I wouldn’t be able to tell you.
Then I wake up a few seconds or at most a minute later.
It’s essential to remember that the reason this process happens with lectures and not, say, during a conversation, is because the information bandwidth is a constant, which means that my brain can (with reasonable confidence) allocate processing resources to something else. A conversation, on the other hand, has high fluctuations in information bandwidth that my brain would have to keep an eye on.
Another equally important point that I haven’t mentioned yet is that in a lecture, the only stimuli that are changing are those directly related to the lecture itself, i.e. the lecturer and his slides. The rest of the room is basically unchanging. So, to push the computer analogy even further, imagine that my brain encodes auditory and visual information via a compression akin to MPEG; in other words, it only pays attention to things that change. If I stop paying attention to the lecturer and his slides, then I’m not paying attention to any external stimuli at all! This provides another compelling reason why I don’t just spontaneously fall asleep while walking around Oxford.
Finally, I think this happens to me rather than to everyone is to do with the balance between my two attentive streams. The possibilities are that lectures (for some reason) are unusually poor at holding my attention, or my imagination is overactive, or my attention-switching mechanism is kerjiggered.
It is, I believe, a very seductive and compelling hypothesis that is more satisfactory than my previous ‘energy conserving brain’ hypothesis – perhaps even worthy of more investigation…