Tuesday, August 28, 2012

Sleep Cycles & Health

"The National Sleep Foundation's 2008 poll showed that 36% of Americans reported driving drowsy or falling asleep while driving; 29% regularly fall asleep or become very sleepy at work; 14% miss family events, work functions, and leisure activities due to sleepiness."
HelpGuide.org:
The quality of your sleep directly affects the quality of your waking life, including your mental sharpness, productivity, emotional balance, creativity, physical vitality, and even your weight. No other activity delivers so many benefits with so little effort!

Circadian Rhythm
Your internal 24-hour sleep-wake cycle, otherwise known as biological clock or circadian rhythm, is regulated by processes in the brain that respond to how long you’ve been awake and the changes between light and dark. At night, your body responds to the loss of daylight by producing melatonin, a hormone that makes you sleepy. During the day, sunlight triggers the brain to inhibit melatonin production so you feel awake and alert.

This sleep-wake cycle can be disrupted by factors such as nightshift work, traveling across time zones, or irregular sleeping patterns, leaving you feeling groggy, disoriented, and sleepy at inconvenient times. The production of melatonin can also be thrown off when you’re deprived of sunlight during the day or exposed to too much artificial light at night, disrupting the sleep-wake cycle and preventing you from getting the sleep you need.

According to the National Institutes of Health, the average adult sleeps less than 7 hours per night. In today’s fast-paced society, 6 or 7 hours of sleep may sound pretty good. In reality, it’s a recipe for chronic sleep deprivation.

While sleep requirements vary slightly from person to person, most healthy adults need between 7.5 to 9 hours of sleep per night to function at their best. Children and teens need even more. And despite the notion that our sleep needs decrease with age, older people still need at least 7.5 to 8 hours of sleep. Since older adults often have trouble sleeping this long at night, daytime naps can help fill in the gap.

NIH:
Health Benefits
“Loss of sleep impairs your higher levels of reasoning, problem-solving and attention to detail,” Mitler explains. Tired people tend to be less productive at work. They’re at a much higher risk for traffic accidents. Lack of sleep also influences your mood, which can affect how you interact with others. A sleep deficit over time can even put you at greater risk for developing depression.

But sleep isn’t just essential for the brain. “Sleep affects almost every tissue in our bodies,” says Dr. Michael Twery, a sleep expert at NIH. “It affects growth and stress hormones, our immune system, appetite, breathing, blood pressure and cardiovascular health.”

Research shows that lack of sleep increases the risk for obesity, heart disease and infections. Throughout the night, your heart rate, breathing rate and blood pressure rise and fall, a process that may be important for cardiovascular health. Your body releases hormones during sleep that help repair cells and control the body’s use of energy. These hormone changes can affect your body weight.

“Ongoing research shows a lack of sleep can produce diabetic-like conditions in otherwise healthy people,” says Mitler.

Recent studies also reveal that sleep can affect the efficiency of vaccinations. Twery described research showing that well-rested people who received the flu vaccine developed stronger protection against the illness.

As people get older, they may not get enough sleep because of illness, medications or sleep disorders. By some estimates, about 70 million Americans of all ages suffer from chronic sleep problems. The 2 most common sleep disorders are insomnia and sleep apnea.
REM Sleep
Just as deep sleep renews the body, REM sleep renews the mind. REM sleep plays a key role in learning and memory. During REM sleep, your brain consolidates and processes the information you’ve learned during the day, forms neural connections that strengthen memory, and replenishes its supply of neurotransmitters, including feel-good chemicals such as serotonin and dopamine that boost your mood during the day.

To get more mind and mood-boosting REM sleep, try sleeping an extra 30 minutes to an hour in the morning, when REM sleep stages are longer. Improving your overall sleep will also increase your REM sleep. If you aren’t getting enough deep sleep, your body will try to make it up first, at the expense of REM sleep.

Sleep Cycles
You may think that once you go to bed, you soon fall into a deep sleep that lasts for most of the night, progressing back into light sleep in the morning when it’s time to wake up. In reality, the sleep cycle is a lot more complicated.

Sleep Architecture
When you chart the sleep stages over the course of the night, the result looks like a city skyline—which is why it is called "sleep architecture"

During the night, your sleep follows a predictable pattern, moving back and forth between deep restorative sleep (deep sleep) and more alert stages and dreaming (REM sleep). Together, the stages of REM and non-REM sleep form a complete sleep cycle. Each cycle typically lasts about 90 minutes and repeats four to six times over the course of a night.

The amount of time you spend in each stage of sleep changes as the night progresses. For example, most deep sleep occurs in the first half of the night. Later in the night, your REM sleep stages become longer, alternating with light Stage 2 sleep. This is why if you are sensitive to waking up in the middle of the night, it is probably in the early morning hours, not immediately after going to bed.


Sleep Debt
While you can’t pay off sleep debt in a night or even a weekend, with a little effort and planning, you can get back on track.
  • Aim for at least 7.5 hours of sleep every night. Make sure you don’t fall farther in debt by blocking off enough time for sleep each night. Consistency is the key.
  • Settle short-term sleep debt with an extra hour or two per night. If you lost 10 hours of sleep, pay the debt back in nightly one or two-hour installments.
  • Keep a sleep diary. Record when you go to bed, when you get up, your total hours of sleep, and how you feel during the day. As you keep track of your sleep, you’ll discover your natural patterns and get to know your sleep needs.
  • Take a sleep vacation to pay off a long-term sleep debt. Pick a two-week period when you have a flexible schedule. Go to bed at the same time every night and allow yourself to sleep until you wake up naturally. No alarm clocks! If you continue to keep the same bedtime and wake up naturally, you’ll eventually dig your way out of debt and arrive at the sleep schedule that’s ideal for you.
  • Make sleep a priority. Just as you schedule time for work and other commitments, you should schedule enough time for sleep. Instead of cutting back on sleep in order to tackle the rest of your daily tasks, put sleep at the top of your to-do list.

More information:
» Benefits of REM Sleep

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