By Dr. Mercola
Both men and women need high-quality sleep to function optimally, but women are far less likely to achieve this than men.
One poll by the National Sleep Foundation (NSF) revealed that two-thirds of women experience a sleep problem at least a few nights each week and up to half said they wake up feeling unrefreshed.1
In a separate NSF poll, women were more likely than men to report experiencing insomnia at least a few times a week, and the average woman between the ages of 30 and 60 reported sleeping just six hours and 41 minutes on weeknights (even though closer to eight hours is optimal).2
Why Are Sleep Troubles More Common in Women Than Men?
There are quite a few reasons — from biological factors to more practical matters like child care — why women's sleep may be lower quality, and more sporadic, than men's.3
Shifts in Hormones
Levels of estrogen and progesterone fluctuate during a woman's menstrual cycle and are thought to affect women's sleep. Dianne Augelli, M.D., a sleep expert at the Weill Cornell Center for Sleep Medicine at New York-Presbyterian, told New York Magazine:4
"Estrogen works on several different neurotransmitter pathways that may have an impact on the regulation of sleep, and progesterone can have a hypnotic property … Fluctuations in these hormones may have an effect on the circadian rhythm."
Pregnancy and Children
Pregnancy brings with it a host of sleep-disrupting symptoms, like physical discomfort, frequent trips to the bathroom, and heartburn. Conditions such as restless legs syndrome and sleep apnea may also begin during pregnancy and interfere with sleep.
After pregnancy, care of the baby, then toddler, further interferes with quality sleep. Even after children start sleeping through the night, many women have trouble sleeping as soundly as they used to.
Menopause brings its own set of troubles for women's sleep, including hot flashes and night sweats. Obstructive sleep apnea also tends to increase in women during the menopausal and post-menopausal years, and a key symptom of this may be insomnia.
Stress, Anxiety and Depression
Women tend to be more vulnerable to feeling sadness and anxiety than men, according to research, and feel the pressures of stress more than their male peers, both at work and at home.
Stomach-churning anxiety, for example, is far more common in women than men, as are feelings of sadness in response to stress, and not being able to stop thinking about that which worries them.5 All of this can interfere with a sound night's sleep.
Circadian Rhythms Change in the Elderly
Elderly people are another population that tends to have increased trouble sleeping. Health issues, such as frequent urination or pain, can keep seniors up at night, as can sleep apnea.
Further, as you get older your body's internal clock gradually adjusts to earlier bedtimes and wakeup times. If you don't listen to your body and go to bed earlier (instead choosing to stay up late), sleep deprivation may result.6
Your circadian rhythm (sleep-wake cycle) actually "drives" the rhythms of biological activity at the cellular level, and certain genes regulate these daily activity patterns.
Researchers from the University of Pittsburgh School of Medicine in Pennsylvania recently looked into the rhythm of such gene activity in the brain and particularly how it changes with age.
By analyzing thousands of genes from brain samples, they found significant changes in the daily rhythms of older people. As reported by Medical News Today:7
"They found that younger people had the daily rhythm in all the classic 'clock' genes. Older people appeared to have lost rhythm in many of these genes, but they also had a set of genes that gained rhythmicity.
Senior investigator Colleen McClung, Ph.D., believes this could explain some of the changes that older people experience in sleep, cognition and mood."
The discovery may also help explain some of the molecular changes that occur in people with depression (which is associated with disruptions to daily routines). It may also help explain why people with dementia may become more agitate and confused in the evening (a phenomenon known as "sundowning.")8
How Changing Your Diet Might Improve Your Sleep
If you're having trouble sleeping, your diet might be the last factor you'd consider changing in order to help — but it should be among the first. Excessive daytime sleepiness and poor sleep quality are common symptoms reported by obese people.
Dietary changes may help to combat this, regardless of body weight, according to new research. The study involved obese mice that were fed either a regular or high-fat diet for eight weeks.
Some of the mice were then switched to the alternative diet for one week, which resulted in weight gain and loss among the high-fat and regular diet groups, respectively.
At Week 9 of the study, the two diet switch groups had similar body weight but significant changes to their sleep/wake cycles, which were thought to be caused by the acute dietary changes. According to the study, which was published in the journal Sleep:9
" … [A]nimals switched to HFD [high-fat diet] (and thus gaining weight) had decreased wake time, increased NREM sleep time, and worsened sleep/wake fragmentation compared to mice switched to RC [regular chow] (which were in weight loss).
These effects were driven by significant sleep/wake changes induced by acute dietary manipulations (Week 8 → Week 9) … Acute dietary manipulations are sufficient to alter sleep and wakefulness independent of body weight and without effects on sleep homeostasis."
The implications of this study are that obese people likely don't need to lose all of their excess weight to begin to experience improvements in sleep. Changing to a healthier diet that jumpstarts weight loss may lead to improved sleep even after just a short time.
Certain Foods Are Known to Help Promote (and Disturb) Sleep
Many people grew up drinking a glass of warm milk before bed to help lull them into sleep, and you may have "graduated" as an adult to a cup of warm chamomile tea, which is known for its calming properties. Certain foods, too, are known for their sleep-inducing effects.
Cherries, for instance, are a natural source of the "sleep hormone" melatonin, and drinking tart cherry juice has been found to be beneficial in improving sleep duration and quality.10
Alternatively, almonds and spinach are rich in magnesium, which is known for promoting sleep and relaxing muscles. In general, eating a high-protein snack several hours before bed may help you sleep, as it can provide the L-tryptophan needed for your melatonin and serotonin production.
Eating a small piece of fruit along with it makes sense, as this can help the tryptophan cross your blood-brain barrier. The opposite also holds true in that certain foods can significantly interfere with your sleep.
Foods and beverages with too much caffeine would certainly be among them, but so would spicy foods before bedtime, which are linked with more time spent awake during the night and taking longer to fall asleep.11 I recommend avoiding before-bed snacks and stopping eating at least three hours before bedtime.
Not only is this important to optimize your mitochondrial function and prevent cellular damage from occurring, but it will also lower your blood sugar during sleep and help minimize damage from too much sugar floating around.
Additionally, it will jumpstart the glycogen depletion process so you can shift to fat-burning mode. A study published in the Proceedings of the National Academy of Sciences is a powerful confirmation of this recommendation, as it found that the mere act of altering your typical eating habits — such as getting up in the middle of the night for a snack — causes a certain protein to desynchronize your internal food clock.12
This can throw you off kilter and set a vicious cycle in motion. Eating too close to bedtime, or very late at night when you'd normally be sleeping, may throw off your body's internal clock and lead to weight gain. Routinely eating at the wrong time may not only disrupt your biological clock and interfere with your sleep, but it may also devastate vital body functions and contribute to disease.
Do You Really Need Eight Hours of Sleep a Night?
It's often said that modern-day humans' sleep suffers from our 24/7 lifestyles. However, UCLA researchers studied pre-industrial, hunter-gatherer societies in Tanzania, Namibia and Bolivia and found they do not sleep more than "modern" humans.
Instead, members of these societies sleep about 5.7 to just over seven hours a night, going to bed several hours after sunset and often awakening before sunrise.13 This seems to suggest that perhaps modern humans don't need as much sleep as we've been told.
However, this was addressed in an interview by Chris Kresser with Dan Pardi, a researcher who works with the Behavioral Sciences Department at Stanford University and the Departments of Neurology and Endocrinology at Leiden University in the Netherlands.
According to Pardi, the sleep duration, which is the length of time the hunter-gatherers actually spent sleeping, was between 5.7 and 7 hours. However, the sleep period, which is the total time spent in bed, was 7 to 8.5 hours a night. As long as you're providing your body with adequate time in bed, it's OK if sometimes you sleep more and sometimes less. Pardi told Chris Kresser:14
"Sometimes you'll sleep more, and sometimes you'll sleep less, but you want to give your body adequate time for what I call 'complete sleep,' which is allowing all of the homeostatic, physiological processes that are taking place during sleep to not be interrupted by artificial means, like an alarm clock … Very few people are going to go to bed at 10 and wake up at 6 and actually get 8 hours of sleep in that interval.
So this study … from a practical perspective, it doesn't change what the recommendations have been and what you've been saying and I've been telling my audience for some time now [to get about eight hours of sleep a night].
… If you worry too much about getting 8 hours of sleep, let's say you're tracking it and you notice you're in bed for 8 but you're getting 6, don't worry. That's not uncommon. A lot of these findings are not actually inconsistent with sleep findings from the lab. You'll bring somebody in the lab, they'll be there for 8 hours, but they'll sleep for 6 hours and 45 minutes."
For more information about the importance of sleep, you can listen to my 2014 interview with Dan Pardi, below.
Download Interview Transcript
The Impact of Temperature on Your Sleep
Another important point Pardi mentioned has to do with how temperature affects your sleep. The UCLA study found that temperature appears to be a major regulator of human sleep duration and timing. According to Current Biology:
"The sleep period consistently occurred during the nighttime period of falling environmental temperature, was not interrupted by extended periods of waking, and terminated, with vasoconstriction, near the nadir of daily ambient temperature. The daily cycle of temperature change, largely eliminated from modern sleep environments, may be a potent natural regulator of sleep."
Indeed, thermoregulation — your body's heat distribution system — is strongly linked to sleep cycles. Even lying down increases sleepiness by redistributing heat in your body, from the core to the periphery.
When you sleep, your body's internal temperature actually drops to its lowest level, generally about four hours after you fall asleep. Scientists believe a cooler bedroom may therefore be most conducive to sleep, since it mimics your body's natural temperature drop.
This is also why taking a warm bath 90 to 120 minutes before bedtime may also help you sleep; it increases your core body temperature, and when it abruptly drops when you get out of the bath, it signals your body that you are ready for sleep. While there's no set consensus as to what temperature will help you sleep the best, in most cases any temperature above 75 degrees Fahrenheit and below 54 degrees will interfere with your sleep.15
Once you're within that range, many factors can influence which temperature is best for you including, of course, your choice of pajamas and bedding. Many people keep their homes too warm (particularly their upstairs bedrooms). Studies show that the optimal room temperature for sleep is actually between 60 to 68 degrees F, so adjust your thermostat (or use of blankets and fans) accordingly.
Interestingly, while a cool room and a lower core temperature may help you sleep better, cold hands and feet will not. Because blood flow is a prime method of distributing heat evenly throughout your body, if your extremities are cold it could be a sign of poor blood flow, which results in sleeplessness. The solution for this is simple: put on a pair of warm socks or place a hot water bottle near your feet.
Quality Sleep Can Come Easy
Like healthy eating and exercise, getting high-quality sleep is something that you can actively work at and improve in your life. Proper "sleep hygiene" is important for both men and women to achieve more restful, restorative sleep. I suggest you read through my full set of 33 healthy sleep guidelines for all of the details. To start, consider implementing the following changes:
- Avoid watching TV or using your computer in the evening, at least an hour or so before going to bed. These devices emit blue light, which tricks your brain into thinking it's still daytime. Normally, your brain starts secreting melatonin between 9 p.m. and 10 p.m., and these devices emit light that may stifle that process. Even the American Medical Association now states:16
"… [N]ighttime electric light can disrupt circadian rhythms in humans and documents the rapidly advancing understanding from basic science of how disruption of circadian rhythmicity affects aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism."
- Make sure you get BRIGHT sun exposure regularly. Your pineal gland produces melatonin roughly in approximation to the contrast of bright sun exposure in the day and complete darkness at night. If you are in darkness all day long, it can't appreciate the difference and will not optimize your melatonin production.
- Sleep in complete darkness, or as close to it as possible. The slightest bit of light in your bedroom can disrupt your body's clock and your pineal gland's melatonin production. Even the tiniest glow from your clock radio could be interfering with your sleep, so cover your radio up at night or get rid of it altogether.
Move all electrical devices at least three feet away from your bed. You may want to cover your windows with drapes or blackout shades. If this isn't possible, wear an eye mask.
- Install a low-wattage yellow, orange or red light bulb if you need a source of light for navigation at night. Light in these bandwidths does not shut down melatonin production in the way that white and blue bandwidth light does. Salt lamps are handy for this purpose. You can also download a free application called F.lux that automatically dims your monitor or screens.17
- Avoid using loud alarm clocks. Being jolted awake each morning can be very stressful. If you are regularly getting enough sleep, you might not even need an alarm.
- Get some sun in the morning, if possible. Your circadian system needs bright light to reset itself. Ten to 15 minutes of morning sunlight will send a strong message to your internal clock that day has arrived, making it less likely to be confused by weaker light signals during the night. More sunlight exposure is required as you age.
- Maintain a regular sleep schedule. You should go to bed and wake up at the same times each day, even on the weekends. This will help your body to get into a sleep rhythm and make it easier to fall asleep and get up in the morning.
- Establish a bedtime routine. This could include meditation, deep breathing, using aromatherapy or essential oils or indulging in a massage from your partner. The key is to find something that makes you feel relaxed, then repeat it each night to help you release the tensions of the day.
- If you can't sleep, don't stay in bed. Lying in bed trying to sleep is frustrating and can create anxiety. If you can't fall asleep, leave your bed and listen to some soft music or read a book until you feel sleepy, then go back to bed and try again.
- Be mindful of electromagnetic fields (EMFs) in your bedroom. EMFs can disrupt your pineal gland and its melatonin production, and may have other negative biological effects as well. A gauss meter is required if you want to measure EMF levels in various areas of your home. Ideally, you should turn off any wireless router while you are sleeping. You don't need the Internet on when you are asleep.