Tag Archive for: sleep

Why Are You Napping?

/in /by

I think people get frustrated with research because, just like I’ve described this week, one study says one thing while another comes to different conclusions. I hope that if you’ve been reading the Memo long enough you won’t be frustrated. In this case, why might studies that seem similar on the surface come up with different results?

First, while the studies seemed to ask the same questions, the studies actually had different objectives. In the Swedish study that showed a reduction in cardiovascular disease (CVD) events for those napping once or twice a week, the subjects were selected because they had not had any cardiac events or diagnosis of CVD. That means that any CVD that took place in the follow-up period was a primary event. In the other two studies, high-risk CVD events were excluded in one but other CVD factors were allowed such as hypertension.

Second, the purpose of the Swedish was designed to look at the development of CVD. The other two studies from Switzerland and the U.K. recruited over 500,000 subjects, but the research questions appeared to be decided after the studies began. There’s nothing wrong with that, but just because you have collected data on many variables, including genetics, doesn’t mean the data collected answer the research questions that were asked.

For example, the premise was that daytime napping causes CVD and hypertension. It seems likely that those conditions could cause fatigue, which would require daytime napping. Even if that were not the case, the subjects appeared to already have problems sleeping, which would impact hormone levels that contribute to CVD such as cortisol levels and many others.

The Bottom Line

These large studies attempted to make sense out of prior research that showed a link between daytime napping and CVD. What I think these studies demonstrate is that the cause of the nap is important. If it’s a planned nap designed to allow digestion or a pause in a long work day, it may not be hazardous to your heart health. However, if a person doesn’t sleep well or has sleep apnea and is fatigued because of that, being forced to nap during the day to recover can indicate a higher risk of developing CVD and hypertension.

Diet, body mass, lack of exercise, and other factors all have a role to play in sleep quality and CVD as well. If you plan your nap, you’re in control. If you’re forced to nap, time to look at your lifestyle and see what you can change.

What are you prepared to do today?

        Dr. Chet

P.S. Just for fun, these are a few of Riley’s more inventive napping positions. Oh, to be that flexible! Maybe the monkey blanket helps.

References:
1. Heart. 2019;105:1793–1798.
2. J Am Heart Assoc. 2022;11:e025969. DOI: 10.1161/JAHA.122.025969.
3. Hypertension. 2022;79:00–00. DOI: 10.1161/HYPERTENSIONAHA.122.19120.

To Nap or Not to Nap

/in /by

About 16 years ago, Paula and I spent several weeks (spread out from March to October) helping our son Matthew build his boat-building shop. The daily routine went something like this: start early, break for lunch, take a 30- to 45-minute nap, then work the rest of the day. Matthew and Kerri live near Charleston, SC, where summer temperatures aren’t really conducive to construction work, so napping during the hottest part of the day made a lot of sense, but we also found we got a lot more accomplished every day.

I’ve used that approach off and on ever since. Recently, a couple studies were published that called into question whether naps were a good idea as they might be related to cardiovascular disease (CVD).

The research news caught my attention because the last time I read a research paper about sleep and napping showed that there was no relationship between napping and cardiovascular disease. In fact, the risk over five years of follow-up was a 42% decrease in CVD events when a person took a nap once or twice a week and no risk if a person napped every day (1).

In the most recent research, there was a relationship between napping and hypertension and napping and CVD in two separate studies with thousands of subjects (2, 3). Why? We’ll delve into why there were different results on Saturday.

What are you prepared to do today?

        Dr. Chet

References:
1. Heart. 2019;105:1793–1798.
2. J Am Heart Assoc. 2022;11:e025969. DOI: 10.1161/JAHA.122.025969.
3. Hypertension. 2022;79:00–00. DOI: 10.1161/HYPERTENSIONAHA.122.19120.

Can Cutting Calories Improve Your Mood?

/in /by

In research like the CALERIE study, there’s a tendency to focus on physical changes but what about mood, depression, and quality of life (QOL)? Did researchers find changes in those variables as well? Let’s take a look. While the two-year span of the data analyzed varied slightly from other phases of the study, physiological results were virtually identical to the other phases I’ve talked about in previous Memos.

Testing Procedures

For those readers familiar with the assessment tools typically used in measuring psychological variables, here’s a list of the instruments they used.

Mood: Beck Depression Inventory-II [BDI-II] and the Profile of Mood States [POMS]

QOL: Rand 36-Item Short Form and Perceived Stress Scale

Sleep: Pittsburgh Sleep Quality Index [PSQI]

Sexual function: Derogatis Interview for Sexual Function Self-report

Results

For simplicity’s sake, I won’t use numbers to report the results, because unless one is familiar with the scale for each assessment it wouldn’t be meaningful. Every following relationship was statistically significant or correlated. Compared with the ad libitum (AL) group, the caloric restriction (CR) group had significantly improved mood, reduced tension, and improved general health and sexual drive at month 24. Sleep duration had improved by month 12 and was sustained through month 24.

Greater percent weight loss in the CR group at month 24 was associated with increased vigor and less mood disturbance, improved general health, and better sleep quality. The researchers concluded that there was no negative impact of CR on psychological variables in normal-weight people.

I have a tendency to put more faith in measurable variables such as blood pressure or heart rate than inventories and questionnaires, but the results demonstrated that all measures moved in a positive direction when restricting calories: better perception of mood, health, QOL, more and better sleep, and even sexual vigor. There are indications that CR may be beneficial even in people who are normal weight.

What are you prepared to do today?

        Dr. Chet

Reference: JAMA Intern Med. 2016 Jun 1;176(6):743-52.

How Exercise Improves Sleep

/in /by

To become the best version of yourself, it takes more than just eating better and moving more. One factor that gets overlooked is sleep.

Sleep patterns change over a lifetime; in addition, isolation during the COVID pandemic can also impact sleep patterns. Moderate to strenuous exercise has long been known to have a positive impact on sleep, but what about people who can’t exercise at a high level? Using a technology called actigraphy, researchers in Hong Kong attempted to find out whether mild exercise can help people with insomnia.

Actigraphy is a noninvasive technique that measures physical activity levels of a subject by means of a wristwatch-like motion-sensing device that can be worn for prolonged periods of time. Researchers recruited 320 participants with a mean age of 67 with most subjects being female. There were 110 in the control group, 105 subjects in the conventional exercise group, and 105 subjects in the tai chi group. Subjects in both exercise groups exercised for one hour, three days per week. The conventional exercise was a combination of brisk walking and weight training for 12 weeks, while the tai chi group attended a 12-week Yang-style, 24-form tai chi training program.

When compared to controls, both the exercise and tai chi groups showed improved sleep efficiency, reductions of wake time after falling asleep, and reduced number of awakenings. The actigraphy and sleep diary reports were consistent; there were no differences between exercise groups in benefits.

There’s good reason to believe that if mild to moderate exercise works for people with insomnia, it will work for anyone who wants more and better sleep. Seems like a good deal to me: invest three hours a week to help your entire body and get better sleep as a plus.

What are you prepared to do today?

        Dr. Chet

Reference: JAMA Network Open. 2021;4(2):e2037199.

How Melatonin Affects Memory

/in /by

Most people understand that melatonin functions as a neurotransmitter and can help with sleep. What is now apparent is that melatonin also has powerful antioxidant capabilities, especially as it’s related to the mitochondria, as well as other neurological functions related to memory, according to new research papers.

Researchers used an interesting test of memory in this study. When mice are exposed to a new object, they spend a lot of time examining it on first exposure; when they’re familiar with objects, they have a tendency to ignore them. Researchers exposed young and older mice to new objects and then gave some of the mice a dose of melatonin and two of its metabolites. All the young mice treated the new object as something familiar the next day. The older mice that were not given melatonin said, “Huh? What’s that?” However, older mice that were given melatonin 15 minutes after exposure seemed to remember the new object up to four days later.

The conclusion was that this is a first step to see if melatonin can help with memory in people with cognitive decline, an initial stage related to Alzheimer’s disease. There’s not enough research to say it will work the same way in humans, but there seems to be no downside to taking melatonin on a regular basis with the exception that we don’t know the dosing. If you’ve been taking melatonin for sleep, you may be getting side benefits.

Insiders and Members
In the New Year’s Day memo, I talked about assessing your current health and fitness. I’ve just posted a new Straight Talk on Health that delves into the details of how to assess each category of health. When you log in at drchet.com, follow the Straight Talk on Health link and check it out.

What are you prepared to do today?

        Dr. Chet

References: J Biochem Mol Toxicol. 2020 Feb;34(2):e22430. doi: 10.1002/jbt.22430.

Is Make-Up Sleep Good for You?

/in /by

The first summer holiday is upon us and I have some good news: if you burn the candle on both ends during the week, you may be able to make up for it by sleeping a little extra on weekends. Based on a Swedish study of over 40,000 subjects tracked over 13 years, consistently getting fewer than five hours of sleep per night was associated with higher mortality. But when subjects were able to get extra sleep on weekends, that risk was cancelled.

My philosophy is that we’re going to be dead a long time, so if you must get less sleep during the week to accomplish all you want, so be it. I’ve often told people who’ve asked that as long as you can turn off the alarm and sleep in at least one day a week, that can help. Now there’s some science to back up what I’ve said for years. True, it’s just an observational study and sleep certainly varies by individual, but make-up sleep may be what you need to keep going through the week.

Enjoy the long weekend, and do yourself a favor: get some extra sleep. It may be just the thing you need for your health.

What are you prepared to do today?

Dr. Chet

 

Reference: J Sleep Res. DOI: 10.1111/jsr.12712.

Sleep More and Quit Eating Sooner

/in /by

Sleep more, eat the same, and lose weight. Seriously? That’s what researchers are going to try to find out. At this point, there’s little question that for most people, lack of sleep messes with the circadian rhythms and negatively impacts glucose metabolism.

But a different research team is looking at another element: how long you eat every day can impact your ability to lose weight. Researchers have done a pilot study looking at eating intervals: the time you eat your first meal until you stop eating for the day. For people devoted to their evening snacks, it can be 16 to 18 hours per day.

In the pilot study, subjects restricted their eating to a period of 10 to 12 hours per day. Over 16 weeks, subjects lost an average of seven pounds. One more thing: they didn’t have to restrict their eating. They ate what they wanted, just in a shorter time interval every day.

This was a pilot study using an app that the researchers developed; they’re recruiting 10,000 subjects to see if the idea will work on a greater scale while collecting additional data. Such as what? Well, maybe you actually eat fewer calories when you eat in smaller time frame even if you eat the same foods. By the way, if you want to be a subject, check out www.mycircadianclock.org to see if you qualify.

Back to the sleep portion. The part that interests me the most is the messed up carbohydrate metabolism by eating when your clock says it’s time to sleep. Getting more sleep is not easy these days, but it just might be worth it.

We’ve all heard people say they cannot lose weight no matter what they do. Well, maybe getting a little more sleep and eating over fewer hours may help. Of course, if you’re a diabetic or hypoglycemic, talk with your doctor. But here’s something simple and cheap you could do: sleep more and eat the same over fewer hours. Will you lose weight? We don’t know, but it’s worth a try.

What are you prepared to do today?

Dr. Chet

 

Reference: doi:10.1001/jama.2017.0653

 

Can You Lose Weight by Sleeping More?

/in /by

That doesn’t seem to make any sense; you’re not going to be as active because you’re sleeping, so how can that help you lose weight? Well, if you’re sleeping you’re not eating, but there must be more to it than that. Let’s go back to the SCN, the pacemaker of rhythms.

Researchers have found that cortisol and melatonin aren’t the only hormones and organs tied to the light-dark cycles. Hundreds if not thousands of genes also respond to light-dark cycles. Glucose metabolism, the processing of sugars, is tied to these cycles; we seem to process sugars better during the light hours than at night. For some reason, eating carbohydrates in the dark hours results in slow processing of carbohydrates. Typically carbohydrate metabolism is a fairly high-energy process using 15 to 20% of the calories in digestion and absorption, but eating in the evening seems to decrease metabolism enough that it could theoretically result in gaining 12.5 pounds in a year.

Theory and life are two different things. Research on rodents shows that if researchers flip their cycle by feeding them in opposition to their rhythms—they’re day-sleepers, so they’re the opposite of us—they gain more weight when fed the same diet than mice fed during their normal cycle.

What about humans? Is there a solution? Skinny rats are fine, but what’s in it for us? We’ll wrap this up on Saturday.

What are you prepared to do today?

Dr. Chet

 

Reference: doi:10.1001/jama.2017.0653

 

Could Your Rhythms Be Keeping You Fat?

/in /by

You eat well and you exercise, but you still can’t lose any weight. What if the answer was in the natural rhythms of your body? I’m not talking about dance moves; I’m talking about circadian rhythms, the natural 24-hour cycles based on day and night. Since we can pretty much control the amount of light indoors 24-hours per day, our natural rhythms can be in disarray.

I’ve talked about the pacemaker of the heart several times over the years. It turns out that there’s an area in the brain called the superchiasmatic nucleus (SCN) that acts as the central pacemaker for circadian rhythms. It’s found in the hypothalamus and for a small group of cells, it seems to do a lot.

In the mornings in response to daylight, the SCN sends signals to raise body temperature and produce hormones such as cortisol. Time to get up! The SCN also responds to light by delaying the release of other hormones such as melatonin that help us sleep. When it gets dark the eyes signal the SCN that it’s night. Melatonin levels rise in the evening and stay elevated throughout the night, promoting sleep.

What does this have to do with being fat and not being able to lose weight? Now that we know how this pacemaker works, it turns out it could be an important factor. I’ll cover recent research the rest of the week.

What are you prepared to do today?

Dr. Chet

 

Reference: www.sleepfoundation.org.

 

Protein Intake and Sleep Quality

/in /by

Today we’re going to look at two studies from Purdue University, Paula’s alma mater, on the role of protein intake and sleep during a weight loss program (1). In the first, 14 subjects were given a diet with an increasing percentage of protein intake. After two weeks on their normal diet, subjects were put on a diet that reduced calories by 750; every four weeks, the protein content was increased, beginning with 10%, then 20%, and finally to 30% protein. Their sleep was assessed using the Pittsburg Sleep Quality test before and then after four weeks on each . . .

We're sorry, but this content is available to Members and Insiders only.

If you're already a DrChet.com Member or Insider, click on the Membership Login link on the top menu. Members may upgrade to Insider by going to the Store and clicking Membership; your membership fee will be prorated automatically.