The Relationship Between Sweat and Sleep

Jan. 10, 2014

By Medical Discovery News

Sweat and sleep

If only getting to sleep were really as easy as counting sheep. Over half of Americans admit to struggling with insomnia a few nights a week. And the loss of sleep doesn’t just make a person tired, it can affect how long they live. People who an average of six or fewer hours of sleep each night had higher mortality rates than those who slept seven or more. New research has provided more insight into how people can overcome or prevent insomnia.

Problems falling asleep initially, waking up during the night and then having problems getting back to sleep, feeling tired upon waking in the morning, and waking up before the alarm all count as insomnia – it’s both the ability to fall asleep and stay asleep. There are two different types: primary, a direct issue with sleep, and secondary, sleep issues caused by an underlying medical condition like depression, asthma, and overuse of alcohol. Insomnia can lead to other serious medical issues including memory problems, depression, heart disease, and car accidents. 

Common causes of insomnia include stress, emotional issues, physical discomfort, medications, disruptions in a person’s schedule, and environmental disturbances like light, noise, and temperature. Many suffering from insomnia rely on medications such as sleeping pills and sedatives, the most common being over-the-counter antihistamines. But these drugs can come with significant side effects, particularly for the elderly. Cognitive behavioral therapy, which changes ways of thinking to improve behavior, is recommended for insomnia.

Evidence shows the best ways to prevent insomnia are to maintain a regular schedule, avoid caffeine for the eight hours before bed, and especially get some exercise. While research has long shown the positive relationship between exercise and sleep, a recent study has led scientists at Northwestern University to conclude that sleep may influence exercise more than exercise influences sleep.    

This experiment involved a group of women diagnosed with insomnia, divided into two groups: an exercise and an inactive group. The exercise group performed 30 minutes of moderate exercise several times a week for 16 weeks while the other group was inactive. The results were encouraging, since those in the active group slept 45-60 minutes longer each night, woke less frequently, and felt more energized during the day. 

The surprise came when the scientists took a detailed look at the diaries the women kept of their exercise and sleep. The effect of exercise seemed to take longer than expected – a full four months. Also, most did not report sleeping better on the nights after they exercised, but that a good night’s sleep helped them exercise better the next day. 

People without sleep issues typically experience a more restful night’s sleep after exercising, so why is this not the case for people with insomnia? It may be that those with sleep disorders are different neurologically. They may have hyper-arousal of the stress system, which takes a prolonged regular exercise regime to overcome. Further research will be able to answer remaining questions about the timing or intensity of exercise, the effect of different types of exercise, and whether this is the case in men as well.

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Have Another Cup

By Medical Discovery News

May 19, 2012

I Own Myself... Don't I?

During the morning rush or the afternoon lull, Americans all seem to reach for a pick-me-up using the same thing – caffeine, whether it be coffee, soda or tea. The human love affair with caffeine dates back 500,000 years when Paleolithic man drank tea. While people today use caffeine as a stimulant, experiments have not been able to prove it actually improves cognitive performance, meaning it doesn’t help someone memorize or retain facts for an upcoming exam.

That hasn’t stopped scientists from studying caffeine to understand its effects on the brain. Now, a new report joins a short list of studies showing a shot of Red Bull could enhance mental acuity.  Serena Dudek of the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., is co-author of the study. In experiments with rats, her team found caffeine jolts neurons in an area deep inside the brain responsible for forming, organizing and storing memory.

Caffeine alters brain chemistry because the molecule is small enough to enter the brain and interrupt normal nerve cell functions. In particular, it interferes with a process responsible for sleepiness. People get sleepy because as the day wears on, a chemical in the brain called adenosine builds up. This neurotransmitter protects the brain and keeps it from overworking by binding with nerve cells to slow their activity. As neurons slow down, a person gets sleepy; however, as they sleep, adenosine levels drop, which resets the sleep clock.

Caffeine interrupts this cycle by competing with adenosine for binding to nerve cells. Since caffeine is structurally similar, it can bind to nerve cells, blocking adenosine and stopping the sleep signal. Rather than slow down, the neurons keep working and, in Dudek’s study, they do so in an area of the brain not seen before.

When researchers gave rats the caffeine equivalent to two cups of coffee, a small amount compared with the massive doses used in other studies, they measured the electrical signals of neurons in an area of the hippocampus called CA2. The cells there responded with a huge burst of electrical activity, and the higher the dose of caffeine, the greater the response.

Scientists were able to replicate the experiment on CA2 nerve cells grown in a petri dish.  After only five minutes of exposure to caffeine, these nerve cells were still activated three hours later. If human CA2 neurons respond the same way, this area of the brain may be the most sensitive to caffeine.

The results suggest caffeine may temporarily stimulate mental sharpness and could have a role in learning, which makes sense because the hippocampus, a set of seahorse-shaped organs behind the ears, is responsible for organizing and developing memory. That’s why London cab drivers who learn incredibly complex traffic routes have an enlarged hippocampus.

The study’s results, though on rats, may give a better understanding of caffeine’s effects on the human brain. If caffeine does enhance memory, the 80 to 90 percent of Americans who swear by their daily caffeine habit have more reason to get another cup.

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