Sleep Is Not for Slackers

Abstract

Sufficient sleep is as important as healthy eating and regular exercise to maintain a healthy lifestyle. However, many individuals do not obtain enough sleep or follow healthy sleep hygiene recommendations. The interaction of both biological and behavioral factors may affect sleep. Recommendations of healthy sleep habits that may assist in improving sleep quality and quantity are discussed in this article.

‘Controlled laboratory-based studies have shown that restricted or insufficient sleep results in poorer physical health outcomes.’

Healthy sleep habits are commonly recommended, but often neglected. In our 24/7 society many people think that “sleep is for slackers,” “I’ll sleep when I’m dead,” or “sleep is a waste of my time.” However, what is lost in these prevalent beliefs is the significant impact that deficient sleep has on health outcomes. As discussed by Terre ¹ in this issue, controlled laboratory-based studies have shown that restricted or insufficient sleep results in poorer physical health outcomes, including hypertension, ² increased heart rate, poor immune functioning,^3,4 abnormal glucose metabolism, ⁵ and increased caloric intake and weight gain.^6,7 In addition, neurobehavioral functioning and mood are also significantly impaired when individuals do not obtain sufficient sleep.^8,9

The 2011 NIH National Sleep Disorders Research plan defined deficient sleep as a “deficit in the quantity or quality of sleep obtained vs. the amount needed for optimal health, performance, and well-being.” ¹⁰ Deficient sleep can be a result of a sleep disorder, such as obstructive sleep apnea or insomnia, that disrupts sleep quantity and/or quality. But sleep is also a health behavior, as important as diet and exercise. Buysse recently defined sleep health as “a multidimensional pattern of sleep-wakefulness, adapted to individual, social, and environmental demands, that promotes physical and mental well-being. Good sleep health is characterized by subjective satisfaction, appropriate timing, adequate duration, high efficiency, and sustained alertness during waking hours.”^11(p12) Rather than focusing on a single sleep disorder, this definition recognizes sleep as a health behavior, highlighting how sleep is influenced by an individual’s behaviors as well as social and environmental demands.

Similar to the recommendations to eat 5 fruits and vegetables a day, exercise 30 minutes per day, and brush and floss twice a day, the recommendations for sleep health are well known, in particular, maintain a consistent sleep schedule, have a bedtime routine every night, and limit caffeine in the late afternoon and evening.^12,13 However, without an understanding of why these recommendations are important, people are less likely to have healthy sleep habits.

Biology of Sleep

Sleep homeostasis is the pressure (or need) to sleep, which is very high in the first part of the night, and decreases with sleep.^14,15 This homeostasis depends on the hours of wakefulness and the hours of sleep. The longer one is awake, the more they need to sleep. For adults, more than 16 hours of wakefulness results in poorer neurobehavioral functioning and mood. ⁸ Although many people believe they can “push through” late day sleepiness, they are likely not performing at their best. This can be especially problematic if they are driving long distances or engaging in activities where sound judgment and rapid decision making are necessary. For example, medical errors have been shown to increase when physicians and nurses have extended shifts.^16-19 In addition, one of the recommendations when adults experience insomnia is to not nap, so that sleep homeostasis is not affected. This is because napping will relieve some of the sleep pressure that accumulates during the day, with the result being difficulties initiating sleep at bedtime.

Our circadian rhythm, or internal clock, provides a sleep–wake rhythm that is independent of how long one is awake and asleep.^14,15 Because the circadian rhythm runs on a slightly greater than 24-hour clock, we are constantly using external cues (called zeitgeibers or time givers) to keep our internal clock in check. The most significant of these cues is the light–dark cycle, as this regulates melatonin. With the onset of darkness in the early evening, melatonin is released to provide a cue that sleep should be coming soon. In the morning, bright light suppresses melatonin. People notice their circadian rhythms when daylight saving time starts (ie, when time “springs forward” an hour), as their internal clock is not ready to sleep when the wall clock indicates that it is bedtime. But within a few days most people are able to quickly adjust to the new time.

When sleep schedules are variable, however, this can result in “social jetlag.” ²⁰ For example, staying up later than normal and sleeping in on the weekends (by 2 or more hours) is similar to flying from the east coast to the west coast every weekend. At the end of the weekend, the internal clock has shifted to west coast time resulting in not feeling sleepy when it is bedtime on the east coast. This makes sleep initiation difficult, and on Monday morning, waking up even more difficult. This results in a sleep deficit, despite efforts to “catch up” on lost sleep. Maintaining healthy sleep habits assists the sleep homeostasis and circadian rhythm to work together to facilitate rapid sleep onset at bedtime, sleep maintenance during the night, and wakefulness throughout the day.

Behaviors Affecting Sleep

Because biological and behavioral factors interact to regulate sleep, it is also important to consider the role of behavioral factors that influence sleep. For example, inconsistent sleep schedules can result in poor quality or deficient sleep duration. The use of technology late in the day emits light that can suppress melatonin, making sleep onset more difficult. ²¹ Although healthy sleep habits alone are not sufficient to treat sleep disorders such as insomnia, for most people changing sleep hygiene may be sufficient to improve sleep quantity and quality.^22,23 The following are several recommendations to improve sleep.

Healthy Sleep Habits

Have a Consistent Sleep Schedule

In order to keep the circadian rhythm aligned, and to build up sufficient sleep pressure, it is important to go to bed and wake up at about the same time on both weeknights and weekend nights. Bedtime and wake time should not differ from day to day by more than about an hour.

Establish a Regular, Relaxing Bedtime Routine

While electronic devices have on and off switches, our brains and bodies do not. Thus, it is important to make the 15 to 30 minutes before bed a wind-down time, with a consistent routine to help prepare our bodies for sleep. The use of electronics that emit a lot of light and engaging in stressful activities such as paying bills is discouraged. Rather, it is recommended to engage in a relaxing activity, such as reading a book or magazine or listening to soothing music.

Create an Environment That Is Only for Sleeping

The bedroom should be comfortable, quiet, and dark. Additionally, the room should not be too warm (more than 75°F) as warm temperatures can interfere with sleep. Because of the light emitted by technology, as well as the engaging properties that make it hard to shut devices off, bedrooms should be technology free.

Exercise Regularly

The best time to exercise is first thing in the morning or in the late afternoon. However, a recent study suggests that exercise at any point, other than right before bed, can help facilitate sleep. ²⁴

Enjoy the Sunshine!

Bright light in the morning is essential for keeping the circadian rhythm on track. For this reason, it is important to spend time outside every day, especially in the morning, as exposure to sunlight or bright light helps keep the body’s internal clock on track. ²⁵

Avoid Naps

Because napping alleviates sleep pressure, an afternoon nap can make it more difficult to fall asleep at bedtime. It is recommended that nap time is limited to 45 minutes in the early afternoon (no later than 2 pm). One might feel groggy on awakening (called sleep inertia), but should feel better after a few minutes.

Do Not Consume Caffeine After 4 pm or Within 4 to 6 Hours of Bedtime

Caffeine, which is wake promoting, has a half-life of 4 to 6 hours, and thus should be limited in the late afternoon and early evening. ²⁶ Be aware of all the things that have caffeine (and how much caffeine), including caffeinated sodas, coffee, iced tea, and chocolate. Some medications also contain caffeine, and many products such as maple syrup, beef jerky, and even water can now be found with caffeine.

Do Not Drink Alcohol Later Than 2 Hours Prior to Bedtime

Alcohol acts as a sedative and can be sleep promoting. However, it will interfere with the continuity of sleep, causing one to awaken during the night, contributing to a nonrestful night of sleep. ²⁷

Conclusion

Along with diet and exercise, sufficient sleep is important for individuals to maintain a healthy lifestyle and ensure well-being. Health care professionals should encourage patients to make sleep a priority and regularly follow the recommendations for establishing healthy sleep habits. Patients should also be encouraged to discuss any persisting difficulties with sleep or daytime alertness with their primary care provider as further evaluation for an underlying sleep disorder (eg, obstructive sleep apnea) may be warranted.