Slow Wave Sleep

Nothing much to report from last night’s dreams except some unreasonably tiny baby mice.  They had the physical proportions of adult mice, but were small like pinkies.

So today I’ll jump to a study topic: Slow Wave Sleep.

Slow Wave Sleep (SWS) is also known as Stage 3 sleep (previously Stage 3 and Stage 4, but has been combined recently). It precedes REM sleep and is actually much deeper. It is most difficult to wake someone from this stage of sleep. If you’ve ever gotten to bed late and completely missed your alarm clock, you can probably blame this stage. While it is a Non-Rapid Eye Movement (NREM) stage, dreaming still occurs. The nature of the dreams are different from REM in that they are more normal, thought-like, and repetitive. SWS seems to be a way of solidifying skills or patterns you were learning while awake (edit: there is still some disagreement about the processing of procedural memory, and whether it occurs in SWS or REM). This would be the same stage of sleep where you might experience a seemingly endless game of Tetris or Bejeweled, or you might dream that you are at work carrying out your daily tasks. It’s not very restful, and if you are roused from SWS, you may suffer the effects of sleep inertia. This is a period of impaired cognitive ability that could last as long as 30 minutes after waking.

Being awakened consistently during the SWS stage, your body will adjust to compensate. It will sacrifice some REM time to make up time in SWS. This is dangerous, however, in the fact that once you are given the opportunity to catch up on sleep, your body will go into REM rebound. This highly emotional stage could cause you to experience symptoms similar to depression and bipolar disorder. I think it is relevant to point out that sleep deprivation has been used to treat depression, due to a build up of sleep-promoting chemicals in the body (serotonin, for one), but once the patient is allowed to sleep, the depression returns. You can artificially achieve this effect through use of SSRIs (selective serotonin reuptake inhibitors), which will increase the duration of SWS, again at the expense of REM sleep.

Other ways to increase SWS sleep are determined by the period of wakefulness, body heat, physical activity and even heavy ingestion of carbohydrates. These aren’t generally recommended, because REM sleep is vital for rest. The best plan is to get plenty of sleep on as consistent a schedule as possible. Don’t work yourself to death all week on insufficient sleep with the plan to catch up on your days off. That’s a ticket to depression. I’ve been there and it’s not fun. Actually, I blamed the job for my mental state and wasn’t surprised that when I quit the job, I didn’t need the depression/anxiety meds anymore. What I didn’t realize at the time was that my issue could have been REM rebound from an imbalanced sleep schedule.

I don’t want to sell short the benefits of SWS. It is absolutely necessary to the secretion of growth hormones during puberty. It is quite literally possible to have a growth spurt overnight and wake up a new person. Glucose metabolism also increases during this stage due to increased mental activity.

Later this month, I would also like to cover REM sleep and sleep paralysis. If you have a topic of specific interest regarding sleep, leave a comment below.