Good Night, Sleep Tight
Sleep is the one thing that humans are unable to give up for any length of time. Even more so than water or food, our body simply shuts down when deprived of sleep. Yet, according to the American Academy of Sleep Medicine (AASM), “more than 100 million Americans of all ages … regularly fail to get a good night’s sleep” for one reason or another, leading to “a lowered quality of life and reduced personal health.”
Sleep is essential for tissue and cell repair, detoxification, and replenishing energy. Yet, while seemingly at rest, it also allows us to sort and store our memories and experiences, and somehow contributes to enhanced learning and mental performance. We still have much to discover about how sleep actually “works” to restore our bodies and our minds, and the growing field of research is beginning to uncover the details of what happens when we are “at rest.”
In his book, The Promise of Sleep, Dr. William C. Dement writes that “most of us have the idea that sleep is a cessation of all activity, an oblivion we slip into where nothing happens.” In fact, this is far from the truth. Dr. Dement explains that “During sleep the brain releases new combinations of the hormones and chemical messengers that stimulate cellular activity throughout the body. … the sleeping brain actually appears to be more active than it is while awake.”
Stages of Sleep
There are at least five different recognizable stages of sleep, signified by very different types of brain wave activity and other physiological responses, such as heart rate, breathing, and body temperature. A discussion of the brain wave activity is beyond the scope of this newsletter, but the stages can be simply characterized as follows:
- Stage 1 occurs when first entering a relaxed, half-awake state of light sleep. Considered the period of time when we’re actually “falling asleep,” stage 1 can last from a few seconds to a few minutes. If aroused during stage 1, we feel as if we have not yet been asleep.
- Stage 2 is marked by further muscle relaxation, accompanied by increasingly slower heart rate and breathing, and lowering of our body temperature. Physical movement diminishes as our muscle tensions ease and we become oblivious to outside noises and stimulation. This stage typically lasts about 10 to 20 minutes. If awakened, we are likely to feel as if we had been asleep.
- Stages 3 and 4 are the deepest, most rejuvenating stages of sleep – the kind we need to truly feel rested – with stage 4 being more intense or deeper than stage 3. It is very difficult to wake up during these stages. One of the reasons researchers believe that this is the restorative period of sleep is that pulses of growth hormone, which is essential for building and rebuilding tissue, are secreted during these stages. The amount of time spent in stages 3 and 4 diminishes as we age, and the resulting decrease in tissue restoration is thought to be part of the aging process.
- Stage 5 or REM sleep typically first occurs about 70 to 90 minutes after the onset of sleep, and is when dreams occur. REM stands for “rapid eye movement” because of the way that the eyes dart around during dream sequences. Other physiological changes that may occur include accelerated heart rate and respiration, accompanied by twitching of the face and limbs.The first session of REM sleep tends to be short, just a few minutes, but the length tends to increase throughout the night, with the last period potentially lasting 20 to 40 minutes. Most REM sleep occurs in the last third of the night or early-morning hours, which may explain why we are able to remember our dreams when we wake up.
As we progress through these stages, we go deeper into sleep, achieving higher levels of restoration or rejuvenation. The transition through the stages is somewhat linear, but also cyclical, and we may go in and out of the various stages of REM and non-REM sleep several times throughout the night. Light sleepers, or those with sleep troubles, may not reach stages 3, 4, or REM sleep every night, leaving them feeling tired and unrested—no matter how long they have been “asleep.”
Deep, restorative sleep is one of the most important factors in our overall health and well-being throughout our entire lives. However, as we age, our sleep needs and cycles change, leading to changes in our sleep patterns.
The early years are characterized by many hours of deep sleep. Infants typically sleep 16 to 18 hours a day; by the time they approach age three, toddlers sleep closer to 12 hours a day. Children’s sleep needs decline further as they grow older until their daily requirement settles at about 10 hours, continuing into adolescence.
It makes sense that babies and young children spend a lot of their sleep time in deep sleep because of their need for building muscle and repairing tissues and cells. Metabolic activity and body temperature both decrease during sleep, which conserves energy and provides a chance for tissues to grow and refuel. In addition to the spurts of growth hormone mentioned earlier, the blood supply to the muscles also increases, allowing the body to recover from the physical stresses of the day before. And, in the early morning hours just before waking, cortisol levels peak to help the body prepare for the demands of the day ahead.
The sleep cycle begins to change dramatically when puberty hits, and “hormonal developments are integrally tied to changes in teenagers’ sleep” according to Dr. Dement. Levels of the sex hormones such as testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) begin to surge during puberty, and are produced in greater amounts during periods of sleep in both girls and boys. The onset of puberty is also characterized by a significant rise in the amount of growth hormone secreted, along with a decrease in the level of melatonin secreted. The decrease in melatonin, which is the key hormone that regulates the body’s internal clock, helps explain why teenagers tend to become more “owl-like” as they prefer to stay up later at night. They actually have more difficulty falling asleep at what their parents consider to be the proper bedtime, partially because of the drop in their melatonin level, and then are very hard to wake up in the morning for school because they may be in deep stages of sleep. In this way, adolescents can easily become sleep deprived—and even more impaired than others—because they still require about 10 hours of sleep per night.
The sleep habits of young adults continue to change as they juggle their independence, social lives, and demands of school or career. The reasons for these changes have as much to do with the lifestyles and demands at different phases in life as they do to changes in circadian rhythm or internal body clock (see Our Internal Body Clock). Eventually, the patterns of middle-aged adults and seniors tend to become more like that of a “lark” whereby they fall asleep and rise earlier.
The amount of sleep we need, and the amount we’re usually able to get, continues to decline as we get older. Young adults typically get as many as three to four hours of deep REM sleep a night, and that amount declines to less than two hours for seniors. Between the ages of 40 and 65, we average about seven hours each night and, as we age, we enjoy less recognizable deep sleep, which means that the quality of our sleep decreases. As soon as restful sleep eludes us, we’re likely to begin to fret about it because it is difficult, if not impossible, to avoid the effects of poor sleep.
Sleep Debt and Its Effects
Most of us need about seven to nine hours of sleep each night for optimal functioning, but it’s probably no surprise that most of us get less than that. Every time we deprive ourselves of the sleep we need, even if it is only a few minutes a day, that period of sleep loss accumulates into a sleep debt. Eventually that loss can overcome us, causing us to be irritable and lash out, act irrationally, make mistakes, perform poorly at school or work, or even fall asleep unexpectedly.
According to a series of studies described by Dr. Dement, we can avoid dangerously high sleep debt by adding back a relatively small amount of sleep to our normal routine. The evidence suggests that accumulated lost sleep must be paid back at some time, hour for hour, and those who have succeeded in lowering their sleep debt usually report gaining a new sense of well-being. “If you miss three hours one night, you must sleep 11 hours the next night (three plus your normal eight) in order to feel alert throughout the day,” writes Dr. Dement. While it may be difficult to pay it back in one lump sum, it is important to work at keeping your sleep hours paid up, even if you do it just a few minutes at a time.
The long-term effects of sleep deprivation appear to be cumulative, so it is important to pay back sleep debt to avoid chronic health issues down the road. In addition to the obvious negative effects on alertness and cognitive function, studies have shown that sleep loss may speed up some aspects of aging and alter hormone levels. Sleep-deprived individuals have been found to have higher nighttime levels of the stress hormone cortisol and lower levels of thyroid-stimulating hormone, both of which are involved in regulating metabolism.
Other medical conditions potentially linked to chronic sleep deprivation are a weakened immune system, hypertension, heart disease, type-2 diabetes, and even obesity. Recent studies indicate that a chronic lack of sleep can lead to a deficiency of leptin, a hormone that controls appetite. Without adequate leptin levels, we tend to crave carbohydrates—even after eating—which can lead to overeating and contribute to obesity.
Hormones and Sleep
Many different hormones are linked to or related to sleep; when their levels change or fluctuate, sleep is often affected. A hormone deficiency or imbalance can contribute to exhaustion and waking up feeling tired, among other symptoms. According to Dr. Thierry Hertoghe in his book The Hormone Solution, “correcting hormonal deficiencies can restore the days of sound, refreshing sleep” for many people. The key hormones affecting or related to sleep include:
- Melatonin, known as the “hormone of darkness,” is produced at night by the pineal gland and is the major hormone that regulates and promotes good sleep. Melatonin lowers body temperature and this function may be why it has such a significant effect. A decrease in melatonin levels, such as is found in women with PMS, can lead to trouble falling asleep, falling back asleep after waking up, or experiencing anxious or agitated sleep.
- Human Growth Hormone (HGH), which is secreted by the pituitary gland, is needed throughout life for growth, development, and repair of body tissues. It is secreted early in the night, at the onset of sleep, and a deficiency in growth hormone can lead to the same symptoms as described for melatonin deficiency.
- Cortisol stimulates the type of slow-wave, restorative sleep found in stages 3 and 4, as well as the production of growth hormone. Cortisol levels typically rise in the late morning and early afternoon, and then decrease in the evening. A deficiency in this hormone can leave you feeling unrefreshed upon awakening, even if you have slept through the night, because its purpose during sleep is to mobilize energy stores for the coming day.
- Thyroid Hormones have also been shown to improve sleep quality. In addition to causing the same symptoms as described for melatonin, growth hormone, and cortisol, a deficiency in thyroid hormones may cause waking up with a swollen face and puffy eyelids.
- Estrogens regulate the production of many of the key hormones that are secreted when we sleep, including melatonin, HGH, and cortisol, so changes in estrogen levels may profoundly affect sleep. Estrogens are believed to play a role in enhancing REM sleep and, as their levels decline, REM sleep may be frequently disrupted, leading to exhaustion.
- Progesterone appears to reduce the amount of time it takes to fall sleep, as well as the number of wakeful disruptions after succumbing to sleep. Studies suggest that progesterone has a calming and sometimes sedative effect. A deficiency in progesterone may lead to trouble falling asleep.
- Testosterone’s role in sleep is not as well understood, but the AASM reports that women are twice as likely as men to have sleep problems, which may reinforce that it does play a significant role. Like many of the other sex hormones, a testosterone deficiency has been linked to feelings of fatigue despite sleeping through the night.
Women and Sleep
The powerful role that hormones play in sleep helps us understand why so many women have difficulty falling or staying asleep, especially during times when their hormones are fluctuating.
The National Sleep Foundation’s Sleep in America poll surveyed over 1,000 women, and the results suggest that the biological conditions unique to women (i.e., menstruation, pregnancy, and menopause) affect sleep quality. The poll found that nearly 70 % of the women surveyed had trouble sleeping at least a few nights per week, with almost 50% reporting having trouble sleeping every night or nearly every night. The resulting sleep deprivation can lead to daytime fatigue, irritability, brain fog, increased anxiety, and depression, among other conditions.
For many women, pregnancy is the first time in their lives when they notice a real change in their ability to sleep. Some may be quick to blame the problem on the discomfort associated with the growing fetus’ movements, but the hormonal changes that accompany pregnancy are more likely the culprits. Sleep researcher Dr. Kathryn Lee found that pregnant women’s sleep becomes disrupted as early as 11 weeks into pregnancy. One of the most common complaints is the need to make more frequent trips to the bathroom throughout the night, even before the expanding uterus begins to press on the bladder. This feeling of the “need to go” is more likely caused at this stage of pregnancy by the increased level of progesterone, which inhibits the contraction of the smooth muscles of the urethra and bladder walls.
A woman’s menstrual cycle may also have an effect, but those effects may be very different for different women. Some women report sleep disturbances due to bloating, cramping, and headaches the week prior to their menstrual flow, while others experience them during their period. The hormonal changes in women with premenstrual syndrome (PMS) include a decrease in melatonin, which when combined with the other discomforts of the menstrual cycle, can add to their sleep troubles.
Sleep disruptions are some of the most common symptoms of perimenopause, and restful sleep eludes many menopausal women for a variety of reasons. In fact, Dr. Walsleben reports that nearly two-thirds of women complain of insomnia during the years leading up to menopause. In The Pause, Dr. Lonnie Barbach reports that “A lack of sustained sleep is the pattern we see with menopause. Women seem to wake up repeatedly during the night because they need to urinate or have a hot flash or night sweat, or for no apparent reason at all.” This is especially true of women who are particularly sensitive to fluctuations in estrogen levels, which can cause bothersome symptoms that interfere with getting a good night’s sleep.
Because estrogens have been shown to enhance and increase the time spent in REM sleep and reduce the time it takes to get to REM sleep, researchers designed studies to determine the effects of estrogen therapy. Placebo-controlled studies involving pre- and post-menopausal women found that estrogen therapy helps women to fall asleep faster, decreases wakefulness after falling asleep, and increases total sleep time.
In the post-menopausal years, women frequently report different sleep problems, including sleep-disordered breathing or loud snoring, which leave them feeling fatigued during the day. According to the AASM, this “may be related to falling progesterone levels, since younger women who experience surgical menopause are also at increased risk of developing sleep-disordered breathing.”
Especially for women, changing hormone levels are almost always at the root of their sleep problems and represent the biggest obstacle to enjoying an uninterrupted night’s sleep. Understanding the hormonal effects, along with addressing environmental factors and lifestyle habits, may be the key to helping women get a good night’s sleep.
Of course, factors other than hormones can be disruptive to your sleep. Sleep problems often begin to occur during young adulthood or middle age due to increasing responsibilities and stress, or life changes such as a new baby or job, or the aging process. While it helps to honestly analyze if any of these may be affecting your sleep, it is also important to realize that there are serious medical conditions that may be the cause for these disruptions.
Some of the more common sleep disorders include:
- Breathing interruptions, which range from those that are subtle enough that they do not wake us but are enough to disrupt our transitions into deeper sleep, to obstructive sleep apnea, in which the throat muscles relax so much that our breathing is impaired. Snoring (especially loud, gasping snoring) is a common symptom of sleep apnea. Depending on the severity, these breathing disorders can cause a drop in oxygen levels during sleep, which can lead to or worsen other medical conditions, such as hypertension, stroke, and heart disease.
- Narcolepsy, which appears to be hereditary, is a dangerous, debilitating disease characterized by uncontrollable urges to sleep during waking hours. Narcoleptic attacks may occur at any time, and those who suffer from them may also hallucinate, have nightmares, or endure sleep paralysis while in a narcoleptic episode.
- Restless leg syndrome (RLS) is characterized by a burning or itching sensation on the legs that results in twitching, tossing, and turning throughout the night. Relief often requires getting up out of bed and walking around until the sensation subsides.
Most often, the disorders mentioned above can be effectively treated. Insomnia and depression are two more common disorders that are less straightforward to treat, and they are often related, as depression may be the underlying cause of insomnia.
Insomnia is considered the common cold of sleep problems, affecting approximately one-third of American adults. It is the most common sleep problem among women; according to the Sleep in America Poll, more than 60% of the women respondents reported experiencing insomnia within the previous month.
Effective treatment of insomnia relies on identifying the underlying cause(s). The cause can be something serious such as depression and, since sleep and mood involve many of the same chemical messengers and hormones, it makes sense that the chemical changes that induce feelings of depression will likely affect sleep as well. Insomnia may also be caused by stress and a hormone imbalance, as mentioned throughout this newsletter.
Whatever the cause, if any of these disruptions are affecting your quality of life, it is important to consult with a healthcare practitioner, especially if you think you may have a hormone imbalance or other medical problem.
The ability to fall asleep, stay asleep, and wake up feeling refreshed seems simple when it happens with little effort, and we tend to take it for granted when it happens so easily. However, we really begin to appreciate how critical sleep is to our overall health and well-being when it becomes problematic. Important factors in getting a good night’s sleep include:
- Eat and drink right. Simple diet and nutrition strategies may help improve your sleep habits, but most important is that you restrict what you eat and drink starting 3-4 hours before bedtime. Sleep experts and health practitioners recommend keeping dinner on the light side by avoiding protein-dense, fatty, spicy, or raw foods. Overeating at bedtime can lead to indigestion and a restless night.
- Avoid nicotine, caffeine, and alcoholic beverages within 4 to 6 hours of bedtime. Alcohol can also interfere with hormone secretion during sleep and negatively impact your natural rhythm.
- Exercise regularly, but early in the day. Another unanimous tip: get regular physical exercise, but avoid vigorous or strenuous activity within three hours of bedtime. While exercise generally helps us relax, exercising too close to bedtime will delay the time it takes for your body to unwind and fall asleep. The hormones and chemicals generated by exercising will increase alertness. Yoga and stretching, on the other hand, are better nighttime activities because they relax you. Taking a nice warm bath following yoga or stretching can also help set the right tone and promote better sleep.
- Establish a bedtime routine. Getting to bed with a conscious intention to sleep, and waking up at about the same time each day helps establish a routine for good sleep habits. If necessary, set your alarm and try to sleep the same number of hours each night. Avoid daytime naps, unless you are overcome with drowsiness or they are a regular part of your sleep routine; limit napping to one hour or less, and finish before mid-afternoon. One of the keys to establishing a bedtime routine is keeping your sleep environment comfortable and primed for sleep: your bedroom should be quiet, cool, and dark, and your bed should be used only for sex and sleeping. Reading or listening to soft music in bed can also help you unwind. If you do not fall asleep within about 15 to 30 minutes after lights out, get up for a few minutes and try your bedtime routine again. Avoid bright lights, demanding tasks, or strenuous activity before getting back into bed.
- Maintain optimum hormone balance. When sleep problems appear to be linked to hormones, it is important to take appropriate action. There are ways of soothing the hormone-related symptoms that can interfere with good sleep (cutting down on salt, caffeine, and alcohol to reduce bloating during PMS, for example), but the best solution may be hormone therapy. Always consult with a licensed healthcare practitioner to analyze your hormone levels and find the hormone solution that is right for you.
- A Woman’s Guide to Sleep by Joyce A. Walsleben, PhD; Three Rivers Press; New York, NY; 2000.
- The Promise of Sleep by William C. Dement, MD, PhD; Dell Publishing; New York, NY; 1999.
- The Hormone Solution: Stay Younger Longer by Thierry Hertoghe, MD; Harmony Books; New York, NY; 2002.
- The National Sleep Foundation Sleep in America Poll, 2007.
- “Alterations in sleep during pregnancy and postpartum: A review of thirty years of research” by Kathryn A. Lee, MD; Sleep Med Rev, 1998.
- The Pause by Lonnie Barbach, PhD; Penguin Books; New York, NY; 1993.
- “Guidelines for the Multiple Sleep Latency Test (MSLT): A Standard Measure of Sleepiness” by MA Carskadon, et al; Sleep, 1986.
- Series of wellness booklets from the American Academy of Sleep Medicine.