Sleep Patterns and Sleep Theories

Circadian Rhythm Our 24 hour biological clock. Light is an external cue that can set the circadian rhythm. Some circadian rhythms are endogenous suggesting the existence of an internal (biological) clock. Our body temperature and awareness changes throughout the day. It is best to take a test or study during your circadian peaks.

Biological pineal glandWhen darkness falls, the eyes indirectly inform the pineal gland (responsible for the body’s natural cycles and registering light and darkness). pineal gland hormone melatonin drowsaffects the brain cells which produce serotonin, a sleep- related transmitter substanceThe pineal gland secretes the hormone melatonin in response to darkness, making us drowsy. This affects the brain cells which produce serotonin, a sleep- related transmitter substance.

Sleep

Brain Waves Alpha waves: slow brain waves of a relaxed, awake state.

Think about brainwaves as the gears on a bicycle. When you get into a stressful situation, such as going up a big hill, you need to be able to switch to a smaller gear so that you are able to pedal at a steady rate. However, since you are in a smaller gear each foot push doesn’t get you quite as far as other gears. So the first few gears on a bike would be like Beta brainwaves, they move fast and are excellent to get you through stressful situations. As you move onto flat terrain you want to switch to a mid-level gear that allows you to pedal at a steady speed that is not too much work on your thighs. These gears are like Alpha waves. But as the grade starts to turn to slightly downhill, you can easily slip into a higher gear and still not work that hard. That slightly higher gear, like Theta waves, the chain on the bike makes fewer revolutions but continues to turn the wheels at the same rate. When you head down a huge hill, you shift into the highest gear to be able to keep moving your feet or you just quit pedaling and let gravity take you away. Delta brainwaves equate to this gear. When you are in deep sleep, your brain is only slightly or not at all active, thus not in full control just like when your zooming down a big hill.

Sleep Stages There are 5 identified stages of sleep. It takes about minutes to pass through the 5 stages. The brain’s waves will change according to the sleep stage you are in. The first four sages and know as NREM sleep. (nonREM) The fifth stage is called REM sleep.

Stage One This is experienced as falling to sleep and is a transition stage between wake and sleep. It usually lasts between 1 and 5 minutes and occupies approximately 2-5 % of a normal night of sleep. Eyes begin to roll slightly. Transition of alpha waves (similar to those present while awake) to theta waves (high amplitude, low frequency (slow)) Hallucinations can occur and feeling of falling.

Stage Two This follows Stage 1 sleep and is the "baseline" of sleep. This stage is part of the 90 minute cycle and occupies approximately 45-60% of sleep.

Stage Three & Four Stages three and four are "Delta" sleep or "slow wave" sleep and may last minutes. –Remember Stage 3 is the transitional stage where Delta waves begin to appear It is called "slow wave" sleep because brain activity slows down dramatically from the "theta" rhythm of Stage 2 to a much slower rhythm called "delta" and the height or amplitude of the waves increases dramatically.

Stage Three and Four (continued) Contrary to popular belief, it is delta sleep that is the "deepest" stage of sleep (not REM) and the most restorative. It is delta sleep that a sleep-deprived person's brain craves the first and foremost. In children, delta sleep can occupy up to 40% of all sleep time and this is what makes children hard or impossible to wake up or "dead asleep" during most of the night.

Stage Five: REM SLEEP REM: Rapid Eye Movement This is a very active stage of sleep. Composes about 20% of a normal nights sleep. Breathing, heart rate and brain wave activity quicken. –Irregular heart rate and blood pressure “Dream sleep” From REM, you go back to Stage 2

REM Body is essentially paralyzed during REM. Genitals become aroused. Erections and clitoral engorgement. “Morning Erections” are from final REM stage. Wet dreams A typical 25 year old man has an erection during half of his sleep. A 65 year old- one quarter.

Sleep Disorders

Insomnia Recurring problems in falling or staying asleep. Not your once in a while (“I have a big test tomorrow”) having trouble getting to sleep episodes. This is temporary insomnia –Generally caused by worry, stress or excitement Insomnia is not defined by the number of hours you sleep every night.

Lack of Sleep Inattention, staring, and tremor of the hands

Sleep Deprivation Psychosis Confusion, disorientation, delusions, and hallucinations

Narcolepsy Characterized by uncontrollable sleep attacks. Lapses directly into REM sleep (usually during times of stress or joy).

Sleep Apnea A sleep disorder characterized by temporary cessations of breathing during sleep and consequent momentary re-awakenings. 1 in 20 people

Sleepwalking (Somnambulism) Sleepwalking is a sleep disorder affecting an estimated 10 percent of all humans at least once in their lives. Sleep walking most often occurs during deep non-REM sleep (stage 3 or stage 4 sleep) early in the night.

Sleepwalking Symptoms and Features: Ambulation (walking or moving about) that occurs during sleep. The onset typically occurs in pre-pubertal children. difficulty in waking the patient during an episode amnesia following an episode episodes typically occur in the first third of the sleep episode polysomnographic monitoring demonstrates the onset of an episode during stage 3 or 4 sleep Fatigue (which is not the same as drowsiness), stress and anxiety

Sleepwalking One common misconception is that a sleep walker should not be awakened. It is not dangerous to awaken a sleep walker, although it is common for the person to be confused or disoriented for a short time on awakening. The only danger is in the sleep walker accidentally harming you in being startled by the means of being woken up. Another misconception is that a person cannot be injured when sleep walking. Actually, injuries caused by such things as tripping and loss of balance are common for sleep walkers.

Infants SIDS--Sudden Infant Death Syndrome –Side or Back “Back to sleep.” –Some believe due to sleep apnea Infants generally sleep in 2-4 hour blocks of time –Feeding

REM Rebound The tendency for REM sleep to increase following REM sleep deprivation, or excessive stress. What will happen if you don’t get a good nights sleep for a week, and then sleep for 10 hours? REM Rebound suggests that there is a need for sleep You will dream a lot.