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As infants we spend about half our time engaged in sleep, and another third when we are older, but it is essential for survival. If you don’t get enough sleep, you risk depression, fatigue and even heart problems. We are not totally sure why it is so important, but it seems that all mammals require sleep. Doctors, pilots, police officers and other shift-workers know very well what happens if you try to go without sleep, when all body processes begin to slow down or get confused.
Sleep activation is an area of much concern. We know that a 24-hour rhythm is important, as is light. Most people adopt a particular body posture, in a specific place and need a pre-bed routine for optimal sleep. Our eyes close and our sense of awareness decreases. But our brain is quite active in its own way. In fact, it is the brain that most requires sleep.
Brain activity tends to alternate between two very different stages. NREM or “non-rapid eye movement” sleep is a slow and passive activity and decreased muscle tone. It is the first stage of sleep and can be further characterized into sub-types. The more tired you are, the longer NREM sleep onset you tend to experience. REM or "rapid eye movement" is the other major sleep stage. It follows NREM, and in addition to rapid eye movement, activation of muscle tone and genital engorgement occurs. Despite this, it is a deeper stage and more difficult to awaken from. This is also the stage associated with increased brain activity and dreams. Dreams are thought to be a conscious experience that begin with hallucinations where there exists perception of objects without sensory input. Dreaming serves a purpose in brain rejuvenation and development. Not everyone dreams in color either, and we tend to recall dreams more vividly if we are woken up immediately after the REM phase. During sleep, we go through cycles of alternating NREM-REM phases. For a good night's sleep to occur we humans need at least 3 or more such cycles during the course of a night.
There are many disorders associated with sleep including sleep apnea, restless leg syndrome, snoring, and chronic insomnia. Entire institutes exist to study these problems. Doctors frequently order sleep studies to investigate problems. Good sleep hygiene is vital. You should attempt to go to sleep at the same time every day. People traveling through time zones can most appreciate the importance of good sleep hygiene. Teenagers are another case in point, since data now exist to support their late night habits. Adolescents tend to need up to 10 hours of sleep nightly, but tend to fall asleep fairly late and are most rested when they arise in the late morning. This seems to be a hard generalization in a society whose secondary education system revolves around early awakening and learning. At the other end, as we get older our sleep requirements fall. Some 80-year-olds function perfectly well on 4 hours sleep. Short daytime naps are acceptable and should be taken within 8 hours of early awakening.
Difficulty falling asleep is perhaps the most common problem that patients seek help for. We tend to suggest refraining from caffeine in the evening, avoiding intense exercise late in the evening and trying to forgo those mini-naps while watching television as the first line of treatment. Using decongestants or other forms of self-medication at night can prevent sleep activation. Some people self medicate with alcohol commonly referred to as a “night-cap” prior to retiring. At times, this can make things worse. Generally, we tend to prescribe mild sedatives and good sleep hygiene when things just don’t straighten themselves out. A good example is shift workers. These individuals need to adjust their sleep patterns every few weeks, which sometimes leads to problems. The sandman does not always visit every night but if you continually wake up non-rested, let your doctor know.
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