Sleep can be divided into two types: REM sleep and non-REM (NREM) sleep. NREM sleep has four stages of increasingly deep sleep. Stage 1 sleep is the lightest, while stage 4 is the deepest.
During normal sleep, you cycle through these types and stages of sleep. But if your sleep is repeatedly interrupted and you cannot cycle normally through REM and NREM sleep, you may feel tired, fatigued, and have trouble concentrating and paying attention while awake. Sleepiness puts you at greater risk for car wrecks and other accidents.
Do you have aching, creeping, crawling, or prickling sensations in your legs
when you lie down or sit still? Those are the classic symptoms of a common
disorder called restless legs syndrome.
An estimated 5% to 15% of adults have restless legs syndrome (RLS), and up
to 19% of pregnant women develop RLS symptoms during pregnancy. Restless legs
syndrome does not cause serious health problems, but can interfere with sleep
and lead to severe fatigue. Here are tips for a symptom-free lifestyle.
If you have trouble getting to sleep or sleeping through the night, if you wake up too early or have a hard time waking up at all, or if you are overly tired during the day, you may have one of the following sleep problems.
Circadian Rhythm Disorders
Typically, people sleep at night -- thanks not only to the conventions of the 9-to-5 workday, but also to the close interaction between our natural sleep and alertness rhythms, which are driven by an internal "clock."
This clock is a small part of the brain called the suprachiasmatic nucleus of the hypothalamus. It sits just above the nerves leaving the back of our eyes. Light and exercise "reset" the clock and can move it forward or backward. Abnormalities related to this clock are called circadian rhythm disorders ("circa" means "about," and "dies" means "day").
Circadian rhythm disorders include jet lag, adjustments to shift work, delayed sleep phase syndrome (you fall asleep and wake up too late), and advanced sleep phase syndrome (you fall asleep and wake up too early).
People who have insomnia don't feel as if they get enough sleep at night. They may have trouble falling asleep or may wake up frequently during the night or early in the morning. Insomnia is a problem if it affects your daytime activities. Insomnia has many possible causes, including stress, anxiety, depression, poor sleep habits, circadian rhythm disorders (such as jet lag), and taking certain medications.
Many adults snore. The noise is produced when the air you inhale rattles over the relaxed tissues of the throat. Snoring can be a problem simply because of the noise it causes. It may also be a marker of a more serious sleep problem called sleep apnea.
Sleep apnea occurs when the upper airway becomes completely or partially blocked, interrupting regular breathing for short periods of time -- which then wakes you up. It can cause severe daytime sleepiness. If left untreated, severe sleep apnea may be associated with high blood pressure and the risk of stroke and heart attack.
Women often experience sleepless nights and daytime fatigue in the first and third trimesters of their pregnancy. During the first trimester, frequent trips to the bathroom and morning sickness may disrupt sleep. Later in pregnancy, vivid dreams and physical discomfort may prevent deep sleep. After delivery, the new baby's care or the mother's postpartum depression may interrupt sleep.