Importance of Sleep
Everybody needs sleep. Sleep is important in maintaining the healthy functioning of the human body, and in fact has been shown in rat studies to be essential for survival.
Sleep affects all aspects of the human body, from immune function, physical performance, memory and concentration, and mood. There is also an increased production of proteins and decreased breakdown during sleep, which can help the body recover after a day of physical exertion.
Stages of Sleep
There are two distinct stages of sleep that alternate in cycles and are distinguished by different types of brain waves – non-REM (stage I through IV) and REM sleep. On average, one complete cycle of sleep, from stage 1 non-REM through REM, takes about 1-1.5 hours. There are four stages of non-REM sleep, ranging from light sleep in stage I, to deep sleep in stages III and IV. From the deep sleep stages, a person would have difficulty awakening, and likely feel groggy upon waking. REM sleep comprises 20-25% of total sleep time and is associated with dreaming. Bouts of REM sleep range from less than 10minutes up to 60 minutes. A person who is very tired may have decreased length of REM sleep, or even none at all. Physiologically, the brain is very active during REM sleep; in addition, heartrate and blood pressure both increase, breathing becomes rapid and irregular, and as the name suggests, there is rapid eye movement.
Different people need different amoungs of sleep. Although it is unknown exactly how many hours a person should sleep, it is thought that 8-8.5 hours is fully restorative for an adult. If a person sleeps less than five hours, risky behaviors begin to emerge in activies requiring judement. A sleep-deprived individual may focus on short-term benefits and thus ignore the potential high cost of an action. The prefrontal and parietal areas of the brain are largely responsible for judgement, impulse control, and attention and visualization. Activity in these areas has been shown to decrease in individuals deprived of sleep for 24 hours.
Studies have shown that sleep deprivation is dangerous. Impairment in higher-order cognitive tasks, and cognitive work requiring simultaneous focus on multiple tasks, occurs with decreased sleep. Coordination in sleep-deprived people can be worse than people who are intoxicated.
Food, Drink, and Sleep
Tryptophan is an essential amino acid that is found in many foods and is particularly plentiful in chocolate, oats, dried dates, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, chickpeas, sunflower seeds, pumpkin seeds, spirulina, and peanuts. Contrary to popular belief, the levels of tryptophan in turkey are comparable to those found in other meats and poultry. Tryptophan causes increased drowsiness because it is actually converted to melatonin once inside the central nervous system. Heavy carbohydrate intake makes tryptophan more available to the brain, hence the reason why carbohydrate heavy foods can cause sleepiness.
Caffeine is widely used to combat sleepiness and fatigue. Caffeine acts as a stimulant by blocking sleep-inducing chemicals and increasing adrenaline production, thus causing an individual to feel more awake. 250mg of caffeine -- about 24 ounces of coffee -- is considered a moderate amount of caffeine. The effect of caffeine can be noted as soon as 15 minutes after consumption; the half-life of caffeine is 6 hours.
Most energy drinks contain a combination of caffeine, essential amino acids, and sugar. While they may have a short-lived alerting affect, oftentimes this is followed by an increase in sleepiness.
There are numerous sleep medications available on the market. Studies have shown that sleep medications can be effectively and safely used to decrease the time to fall asleep, increase total sleep time, decrease awakenings, and improve sleep quality. Although they are considered safe and effective, most physicians only recommend short-term use of sleep medications. These medications should also be used with caution in the elderly, people who need to be alert immediately upon awakening, or in conjunction with alcohol.
Popular prescription medications for sleep include Ambien (zolpidem), Sonata (zaleplon), and Lunesta (Eszoplicone). Ambien and Sonata are approved by the FDA for short-term use; Lunesta is the newest hypnotic on the market, and the only one approved for long-term use. These medications work by interacting with certain receptors in the brain and thus decrease the time to sleep. Benzodiazepines are another class of sleep medications and include flurazepam, Restoril (temazepam), quazepam, estazolam, and triazolam.
Over-the-counter medications include histamine blockers such as Benadryl (diphenhydramine). They are usually inexpensive and can be helpful in many patients. However, these types of medications can have significant side effects such as dry mouth, gastrointestinal symptoms, and restlessness. They should be used with great caution in elderly patients and those taking other medications or drinking alcohol. The effects of these medications can also be quite long-acting, so the effects may last well into the following day.
Melatonin is a naturally occurring hormone that regulates sleepiness, and has gained popularity as a sleep supplement. It is secreted at night by the pineal gland in the brain to induce and maintain sleep, as the final step of pathway initiated by light. Sunlight and artificial light can inhibit release of melatonin. Daytime levels of melatonin are undetectable. Levels stay elevated about 12hrs at night.
Despite its growth in popularity, there is no consistent research showing that melatonin supplements actually work or improve sleep. Because melatonin is contained naturally in some foods, the FDA allows it to be sold as a dietary supplement, which does not require the vigorous studies needed for drugs and medications. Consequently, there is no regulation of the production of melatonin supplments, and listed doses of synthetically manufactured supplements may not be controlled or accurate. Most commercial products raise melatonin levels to much higher than naturally occurring levels. The side effects of increased melatonin levels include fatigue and depression.
The two groups of people who may benefit from melatonin are shift workers and individuals with jet lag. Some studies suggest that if taken in low doses at the appropriate time, melatonin may help these people adjust their sleep-wake cycles.
Naps are not just for kids. Studies performed at NASA have shown that a 40-minute nap improved both performance and alertness in military pilots and astronauts. Even a 10-minute nap can greatly increase short-term alertness without causing grogginess or affecting nighttime sleep. In fact, a recent study in the research journal Sleep concluded that a 10-minute nap actually produced the most benefits in terms of reduced sleepiness and improved cognitive performance. This study showed that a nap lasting 30 minutes or longer is more likely to be followed by sleep inertia – defined as the feeling of grogginess and disorientation after waking from a deep sleep. While sleep inertia is transient, it can have adverse effects for people who need to perform immediately after waking.
As with any sleep time, the keys to napping well are to find a comfortable spot with a good sleeping temperature, and to limit noise and light.
Creating a good sleep environment, plus maintaining a bedtime routine, can help improve one’s nighttime sleep. Keep your room dark, cool, and quiet. Reserve your sleeping room for sleep only. Maintain a consistent routine, whether this involves brushing your teeth, reading a book, or enjoying a light snack.
Of course, these suggestions can be difficult to achieve when outside of your normal bedroom. However, there are some steps you can take to improve your sleeping conditions if sleeping outdoors:
- If possible, use a good mattress pad, not only for comfort but also for insulation from the cold ground.
- Choose a sleeping bag that is appropriate for predicted nighttime temperatures, and if you feel the cold easily then consider using a sleeping bag liner or a warmer bag to keep warm.
- Use an eye mask for additional darkness if necessary.
- Use earplugs if you anticipate noisy surroundings.
- Try to establish as normal a bedtime routine as possible.
“Sleep: Understanding the Basics” – emedicinehealth website, accessed 6/12/2019. Author – Michael Russo.
National Sleep Foundation Website.