Payday 12 October 2000

Pic of the day: Power napping! Even super people need a nap now and then. Screenshot from The Sims.

Napping

The last couple days again haven't seen me catching quite the sleep I could use. Being at work till 6 in the morning isn't caught up with in one day. And it doesn't help that my throat starts to fill with slime after ca 4-5 hours. At that point, it is a good idea to wake up and clear out the system for a while. After that, I tend to be wide awake and not ready to go back to sleep. But luckily, the design for humans includes a cool little function called "nap".

On the surface of it, nap is just a short sleep. But the more I look into it, the more I am convinced that there is a difference. Yes, nap is sleep. But it is somehow different from the longer sleep that we usually have in the night.

***

I react rather badly to coffee. I am not allergic or anything, and I even like the smell and taste of good coffee. But its stimulating effect seems to work mostly locally, by speeding up my digestion to a painful degree. Well, that sure keeps me awake, but it does nothing for productivity. Large amounts of other related stimulants have the same effect: Tea and chocolate being the most common. I can have some more of these, but not enough to keep me awake and alert. So napping comes in really handy for me.

Let me add here that most employers are much more sceptical to napping than to coffee drinking, even when a similar amount of time is used. This probably reflect that leaders tend to be recruited from people who rely on external stimuli. After all, leadership requires not so much intelligence as mania. But I could write a book about that. Not today. Let us just note the fact that napping at work is generally frowned upon, while using a chemical stimulant is considered a human right.

Accordingly, I do not have this grand tradition of workplace napping to draw on. But it does happen now and again, if not exactly every week. I put my arms on my desk, and my forehead on my arms, and nap for 5-10 minutes. Before, I am almost lost in fog. After, I feel refreshed and ready for a few more hours of office "work". It really makes a lot of difference for such a short time.

Usually, though, I manage to get over the sleepiness without actually sleeping, and muddle through somehow. But on the bus home, I am more likely than not to fall asleep ... or rather to nap. It is that particular brand of sleep again: At the same time very light but also irresistible.

***

I've read a couple textbooks on sleep, and more popular science articles than you can shake a nightcap at. But I cannot remember any of them showing real interest in napping. Luce & Segal mentions that sleep deprived test persons eventually lapse into "microsleep", which lasts for a few seconds. I can verify that this is a real possibility. But under less strict conditions, most of us would probably nap well before that. So, what kind of sleep is napping?

Ordinary night sleep is fairly well studied, through years of putting volunteers to bed with electrodes both here and there. (Yes, there too. Surprisingly, they still fall asleep.) We know that sleep follows a 90 minute drumbeat of the brain. During a full 90 minute cycle, we descend to deep, virtually dreamless sleep with long slow "delta" waves. Then drift through a couple lighter stages with fleeting, disjointed imagery, and arrive at REM sleep. This, popularly called "dream sleep", shows a brain activity similar to the waking state, only more intense than most waking activities; but the musles are switched off, so we don't act out our vivid and colorful dreams here. Then the cycle starts anew.

Later research has shown that the 90-minute cycle continues in the background during waking hours. For instance, you will probably breathe more through one nostril than the other at any given time, and this will change gradually to the other side and back during a 90 minute period. And for a certain while every 90 minutes or so, we are more likely to have vivid daydreams and/or become sexually excited for no really good reason.

It is a good chance, then, that the need to nap also manifests more strongly at some point in the 90-minute cycle, and that the short nap corresponds more closely to one particular of the ca 4 dream phases. But which? I do not know. However, when has that ever stopped me from making a bombastic statement? So, educated guess ahead!

The fact that I can nap easily at the bus rules out REM. In REM sleep, I would be losing my cohesion and go limp as a rag doll. The fact that I remain sitting while napping shows that the skeletal muscles only relax partially. Also, there are no vivid, intense dreams. And no erections. (During the nap. I cannot make guarantees for the entire bus ride.) So, one out, three left.

Research on people who suffer from insomnia has shown that they actually sleep quite a bit, and much more than they imagine. (As their family members can attest, the "no sleep all night" is usually a big fat lie, unless they delight in snoring just to irritate.) What these people do, however, is spend most of their sleep time in the two "intermediate" layers of sleep, drifting in a chaotic state inbetween thought and dream. They lack much of both deep sleep and REM sleep.

Due to the refreshing effect of even fairly short naps, I suspect that the nap has at least some of the attributes of deep delta sleep. But that's about as far as I get on this. So what do y'all think?