As the days get longer and we approach the Summer Solstice, the longest day of the year, we may get so excited by the extended hours of daylight that we skimp on our need for sleep. In general, sleep tends to be an area in life that we’ll cut back on in favor of work or play, whether it is trying to cram more time to finish a work project, push through a homework assignment, flipping channels, watching movies, late nights out or even a moonlight stroll. And while we may sometimes think that sleep is an optional activity, or one where the length just doesn’t matter, sleep is an essential part of our daily lives.
While it may seem as though little to nothing is happening in those hours of slumber, sleep is a complex activity, and the more we discover about the mysteries of sleep, the more complex the story becomes. Throughout the night, or our time in bed, we cycle through five different stages of sleep, characterized by different activities. These are stages one through four, and rapid-eye movement (REM) sleep.
We cycle through these stages consecutively, more than once throughout our total sleep time, beginning with stage one, the lightest stage, during which our eyes still move, we may experience muscle twitches and we may still be aware of some aspects of our outer environment before we drift off into stage two. In this stage, we’re transitioning into deep sleep as our eye movements stop and brain waves slow. Stages three and four are collectively known as deep sleep, which are vitally important and restorative for both our minds and bodies. Growth hormone is released, proteins are produced, vital components of the immune system proliferate and nerve cells fire recreating patterns experienced when awake, suggesting important contributions to learning and memory during deep sleep.
The cycles of REM sleep (named for the rapid eye movements that accompany this phase) are when we dream. We experience our first dreams somewhere between 70 to 90 minutes after falling asleep. A complete cycle from the beginning of stage one to the end of REM sleep, usually last anywhere from 90 to 100 minutes. Earlier in the night, we spend more of our time in deep sleep, and as our sleep progresses, we spend more time in the lighter stages, and in dreams.
If we seem to dream more just before we wake up, it is true, we do. Also, we may recollect these dreams, if we want to, and we practice. Some people may keep a dream diary (or recorder) at their bedside. If you do, record them when you first wake up, as the images may fade and be replaced by to-do lists, breakfast or the need to move on with the day. People may ascribe meaning to the stories or symbologies seen in dreams. Beyond the spiritual or symbolic messages in dreams, the time we spend dreaming has an important function in our bodies. For example, studies show that REM sleep is important for our ability to retain or remember what we’ve learned.
Nothing refutes that our morning cup (or cups) of coffee can wake us up and help us feel alert in the morning, particularly after not getting quite enough sleep. Caffeine can later increase the time it takes us to fall asleep, inhibit melatonin production (a hormone associated with sleep cycles) and can interfere with time spent in rejuvenating deep sleep. Both smoking cigarettes (due to the nicotine) and taking antidepressants can reduce the amount of REM sleep experienced. Alcohol may help people fall asleep, but then more time is spent in the lighter stages of sleep, and less in deep sleep and REM sleep.
Just how much sleep we need varies individually. In general, infants need a lot of sleep, 16 hours or more. Fortunately, this drops off as we grow up, to about nine hours for teenagers, and seven to eight for most adults. Even for adults, there can be variance, as some people only need as few as five hours of sleep, while others really do need to sleep 10 hours a night. Under stress, recovering from an illness, during the first few months of pregnancy, or in other situations, people may need more sleep.
What happens if we don’t get enough sleep? Our reaction time slows, our immune system suffers, we may have trouble maintaining a healthy and appropriate weight, recover more slowly from the effects of stress, produce fewer proteins, have trouble with memory…the list goes on. The take-home message: make sure to shut the lights off and get some sleep. In my next column, I’ll talk about hints for getting a good night sleep.
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