Rapid eye movement sleep (REM) sleep is the portion of sleep when there are rapid eye movements (REMs).
Dreams occur during REM sleep. We typically have 3 to 5 periods of REM sleep per night. They occur at intervals of 1-2 hours and are quite variable in length. An episode of REM sleep may last 5 minutes or over an hour. About 20% of sleep is REM sleep. If you sleep 7-8 hours a night, perhaps an hour and half of that time, 90 minutes, is REM sleep.
REM sleep is characterized by a number of other features including rapid, low-voltage brain waves detectable on the electroencephalographic (EEG) recording, irregular breathing and heart rate and involuntary muscle jerks.
By contrast, NREM (non-REM) sleep is dreamless sleep. During NREM, the brain waves on the EEG are typically slow and of high voltage, the breathing and heart rate are slow and regular, the blood pressure is low, and the sleeper is relatively still. NREM sleep is divided into 4 stages of increasing depth of sleep leading to REM sleep. About 80% of sleep is NREM sleep. If you sleep 7-8 hours a night, all but maybe an hour and a half is spent in dreamless NREM sleep.
- Rapid plasma reagin test
A screening blood test for syphilis. Rapid plasma reagin is commonly abbreviated RPR. A negative (“nonreactive”) RPR test result is compatible with a person not having syphilis. However, a person may have a negative RPR test and still have syphilis since, in the early stages of the disease, the RPR often gives negative results. This […]
- Rapid strep test
A diagnostic test commonly used to demonstrate whether streptococcus bacteria (“strep”) are present in the throat. A throat infection with strep needs to be treated with an antibiotic. The traditional test for a strep throat has been a throat culture; the major drawback is that the results of the throat culture take 2 to 3 […]
Breaking out (eruption) of the skin. A rash can be caused by an underlying medical condition, hormonal cycles, allergies, or contact with irritating substances. Treatment depends on the underlying cause of the rash. Medically, a rash is referred to as an exanthem.
- Rash, butterfly
A red, flat facial rash over the bridge of the nose. Over half of patients with systemic lupus erythematosus (SLE) develop this characteristic rash. Because of its shape, it is frequently referred to as the “butterfly rash” of lupus. The butterfly rash of lupus is typically painless and does not itch. Along with inflammation in […]
- Rash, chickenpox
Chickenpox is characterized by a rash, often the first sign of the disease. The rash of chickenpox develops in crops with raised red spots arriving first, progressing to blisters that burst, creating open sores, before crusting over. This process usually starts on the scalp, then the trunk (its area of greatest concentration), and finally the […]