The Year in Sleep

By Dr. Mercola

Considering how important sleep is for survival, very little is known about how much sleep humans actually get each night. There are surveys that have been done, of course, but most of these rely on self-reporting of sleep time, which can be notoriously inaccurate.

If you go to bed at 10 pm and get out of bed at 7 am, you might say you’ve slept for nine hours. In reality, you probably spent at least 15-30 minutes falling asleep and may have woken during the night once or more.

With the advent of fitness-tracking wristbands such as Jawbone’s UP24, however, we now have access to actual sleep data (and more) from wristband users. The data is quite useful on a personal level. It’s also fascinating on a larger scale, as the data reveal insights into sleep patterns from around the world.

What Influences Sleep Patterns Around the Globe?

Jawbone impressively collected data from 1 million UP users (I was one of them) in 2014, revealing a “year in sleep.” There were some differences by country, but three events seemed to influence sleep patterns the most in all countries tracked:

• Sporting events
• Time changes
• Holidays

In the US, for instance, Americans tend to sleep longer on three-day weekends and holidays (like Thanksgiving weekend). Brian Wilt, principal data scientist at Jawbone, detailed 9 more fascinating facts about sleep habits from around the world:¹

1. United States: The practice of moving clocks ahead one hour for daylight saving time in the spring leads to the worst sleep of the year (with Americans losing about 13 minutes of sleep that night).
2. Canada: Canadians woke up 39 minutes early and lost 30 minutes of sleep to watch hockey during the Winter Olympics hockey finals.
3. Germany: Germans lost about an hour of sleep the night their team won the 2014 World Cup.
4. Italy and France: Residents of these countries sleep in much later during the week in August, when most take vacation and businesses often shut down.
5. Russia: Russia made a permanent switch to “winter time” in October 2014, allowing Russians to wake about a half-hour later each day.
6. Japan: People in Japan lost sleep during the World Cup matches, as they had to get up very early to watch the games.
7. Australia: Australians tend to have earlier bedtimes and later wake times in August, and the opposite during December.
8. United Arab Emirates: During the holy month of Ramadan, people stay up close to two hours later because eating before sundown is forbidden.²
9. United Kingdom: The worst night of sleep in the UK was June 14, the night of the England-Italy match during the World Cup. Residents lost an average of 23 minutes of sleep.

Fitness Tracker Data Reveal Most Sleep-Deprived Cities and More

What else can fitness tracker data reveal? Jawbone analyzed data for tens of thousands of Americans in 21 US cities to reveal the most sleep-deprived areas.

What they found was that sleep times were remarkably similar, ranging from a low of 6.82 hours in Houston, Texas to a high of 6.93 hours in Orlando, Florida. On average, that’s just over 6.8 hours of sleep a night.³ Beyond this, the data reveal how natural disasters impact your sleep.

During the South Napa earthquake that hit Northern California in 2014, 93 percent of wristband wearers near the epicenter suddenly woke up at 3:20 am, when the quake hit.⁴ Not surprisingly, most of them had a hard time going back to sleep afterward, and 45 percent of those near the epicenter did not go back to sleep for the rest of the night.

Also interesting, the data can reveal routines and characteristics about different cities. Wilt summed up data of sleep patterns among seven US cities, collected on March 31, 2014, which he described as a “typical night.”

“New Yorkers work hard and play hard, and they’re the first to bed and among the first to rise. Users in Tokyo are among some of the last to go to bed and the first to wake up, since they only average 5 hours and 46 min of night sleep. Dubai has the most leisurely sleep schedule, with 10% of users still asleep by 11am.

In Beijing, you can see workers taking their afternoon workplace naps. We can also see people in Madrid taking their afternoon sleep (although it’s much more common on weekends, with greater than 10% of UP wearers logging a siesta). Only a maximum of 95% of a city is asleep at any given time, since the early risers are awake before the last to sleep are in bed.”⁵

How Much Sleep Are YOU Getting?

You may be surprised at how little sleep you’re actually getting. When I first started using a fitness tracker, I was striving to get 8 hours of sleep, but my Jawbone UP typically recorded me at 7.5 to 7.75.

I have since increased my sleep time, not just time in bed, but total sleep time to over 8 hours per day, and the fitness tracker helped me realize that unless I am asleep, not just in bed, but asleep by 10 pm I won’t get my 8 hours. Gradually I have been able to get this down to 9:30 pm.

So even if you go to bed at a reasonable hour, you might still be lacking in sleep. Aside from using a fitness tracker, how can you tell if you’re getting enough? And how much do you actually need?

Dr. Rubin Naiman -- a clinical psychologist, author, teacher, and the leader in integrative medicine approaches to sleep and dreams – recommends to simply sleep "enough hours so that your energy is sustained through the day without artificial stimulation, with the exception of a daytime nap," which he believes you are biologically programmed for.

I agree with this functional description rather than trying to come up with a specific numeric range. I would add to that guideline, however, the suggestion to watch out for physical or biological symptoms.

For example, when I push myself and don't get high-quality sleep or enough sleep, I'm predisposed to postprandial hypoglycemia. In other words, I have low insulin resistance so when I sleep poorly, it doesn't take much sugar or carbs for it to be easily metabolized and drop my blood sugar—which also makes me really sleepy. When I get enough sleep, I'm far less susceptible to it.

Pay attention to clues your body may be giving you. For instance, if you need an alarm clock to wake up, and you wake up feeling tired and groggy, you probably need to go to sleep earlier (or get more restful sleep).  It’s also said that if you fall asleep within a few minutes of your head hitting the pillow, you’re probably sleep deprived. A well-rested person will take about 10-15 minutes to fall asleep at night.⁶

The Risks of ‘Just Getting By’ on Minimal Sleep

If you’re tired during the day, there’s a good chance you need to get more sleep. Even if you think can “get by” on five or six hours a night, you’re not fooling your body. Sleep deprivation has the same effect on your immune system as physical stress or illness,⁷ which may help explain why lack of sleep is tied to an increased risk of numerous chronic diseases. Sleeping less than six hours per night more than triples your risk of high blood pressure, and women who get less than four hours of shut-eye per night double their chances of dying from heart disease.⁸

According to research from Great Britain, poor or insufficient sleep is actually the strongest predictor for pain in adults over 50,⁹ and people with chronic sleep problems may develop Alzheimer's disease sooner than those who sleep well.¹⁰

Poor sleep can actually impact virtually every aspect of your health, and the reason for this is because your circadian rhythm (sleep-wake cycle) actually "drives" the rhythms of biological activity at the cellular level. Hence disruptions tend to cascade outward throughout your entire body. For example, besides making you more susceptible to physical aches and pains, interrupted or impaired sleep can also:

• Increase your risk of cancer
• Harm your brain by halting new neuron production. Sleep deprivation can increase levels of corticosterone (a stress hormone), resulting in fewer new brain cells being created in your hippocampus
• Contribute to a pre-diabetic state, making you feel hungry even if you've already eaten, which can lead to weight gain
• Contribute to premature aging by interfering with your growth hormone production, normally released by your pituitary gland during deep sleep (and during certain types of exercise, such as high-intensity interval training)
• Increase your risk of dying from any cause

How to Get Truly Restorative Sleep

Download Interview Transcript

Last year I interviewed Dan Pardi on the topic of how to get restorative, health-promoting sleep. Pardi is 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 following three factors are key to determining how restorative your sleep is:

1. Duration— i.e. the number of hours you sleep. Sleep requirements are highly individual, and can change from one day to the next, depending on factors like stress, physical exertion, illness, and pregnancy, just to name a few. But, on average, most people need about eight hours of sleep per night.
2. Timing—i.e. the habit of going to bed at approximately the same time each night. Even if the duration of sleep is the same, when the timing of your sleep is shifted, it's not going to be as restorative.
3. Intensity—This has to do with the different stages that your brain and body goes through over the course of the night, the sequence of them, and how those stages are linked. Some medications will suppress certain phases of sleep, and certain conditions like sleep apnea will lead to fragmented sleep. With these scenarios, even if you're sleeping for an adequate duration and have consistent timing, your sleep will not be as restorative.

If you have these three areas covered and you’re still not sleeping well, maintaining a natural rhythm of exposure to sunlight during the day and darkness at night is one crucial foundational component to consider. The reason why light exposure during the daytime is so important is because it serves as the major synchronizer of your master body clock. To maintain healthy master clock timing, aim to adjust your light exposure to a more natural light rhythm, where you get bright light exposure during the day and limited blue light and bright light exposure once the sun sets.

Pardi recommends getting at least 30-60 minutes of outdoor light exposure during daylight hours in order to "anchor" your master clock rhythm. The ideal time to go outdoors is right around solar noon but any time during daylight hours is useful. Once the sun has set, the converse applies. After sunset you want to avoid light as much as possible in order for your body to secrete melatonin, which helps you feel sleepy.

Ready for the Best Night’s Sleep You’ve Had in a While?

Small adjustments to your daily routine and sleeping area can go a long way to ensure uninterrupted, restful sleep and, thereby, better health. I suggest you read through my full set of 33 healthy sleep guidelines for all of the details, but 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 pm and 10 pm, and these devices emit light that may stifle that process. Even the American Medical Association now states:¹¹

“…nighttime 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.¹²
• Keep the temperature in your bedroom no higher than 70 degrees Fahrenheit. Many people keep their homes too warm (particularly their upstairs bedrooms). Studies show that the optimal room temperature for sleep is between 60 to 68 degrees Fahrenheit.
• Take a hot bath 90 to 120 minutes before bedtime. This increases your core body temperature, and when you get out of the bath it abruptly drops, signaling your body that you are ready to sleep.
• 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.
• 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.