SLEEP

Neurotransmitters and the circadian clock:

Neurotransmitters are chemical messengers between nerve cells and allow communication between the brain and other organs. Sleep is influenced by neurotransmitters and hormones. There are two types of neurotransmitters: excitatory (epinephrine, norepinephrine, dopamine, glutamate, PEA, histamine) and inhibitory (GABA and serotonin). They are involved in all aspects of sleep (waking, transitions, etc.). An imbalance in one or more of these chemical messengers can lead to sleep difficulty. The sleep cycle stems from the interaction between the circadian clock and a separate sleep-wake homeostatic process. The circadian rhythm relates to a periodicity of 24 hours. It is linked to fluctuations of behavioral and physiological functions such as sleep and awaking. It is our internal sleep regulation process.  We use light as cues as well.

REM vs. nREM sleep:

Sleep is prompted by natural cycles of activity in the brain and consists of two basic states: rapid eye movement (REM) sleep and non-rapid eye movement (nREM) sleep which consists of four stages. During sleep, the body cycles between nREM and REM sleep. Usually, we begin the sleep cycle with nREM sleep followed by a short period of REM sleep. Dreams occur only in the REM stages of sleep. During nREM sleep, the body repairs and regenerates tissues, builds bone and muscle, and appears to strengthen the immune system.

Sleep disorders:

Insomnia: a disorder that can make it hard to fall asleep, hard to stay asleep, or both; insomniacs may lie awake for hours before falling asleep; insomniacs may wake up too early and be unable to drift off again, or may wake up repeatedly throughout the night

Sleep apnea: a disorder characterized by abnormal pauses in breathing; people with sleep apnea may stop breathing many times while they sleep and the breathing pauses last several seconds which trigger a switch from deep sleep to light sleep

Restless leg syndrome: a sleep disorder characterized by discomfort which induces the urge to move the legs at rest which makes it difficult to fall asleep; some experience twitching motions during sleep that cause brief awakenings

Narcolepsy: extreme sleepiness during the day; people find it hard to function without naps despite spending enough time in bed at night; narcoleptics enter REM sleep almost immediately without the nREM sleep stages which normally lead up to dream sleep.

Effects from a lack of sleep: fatigue, lethargy, lack of motivation, moodiness, irritability, reduced creativity and problem-solving skills, inability to cope with stress, reduced immunity (frequent colds and infections), concentration and memory problems, weight gain, impaired motors skills and increased risk of accidents, difficulty making decisions, increased health risks and problems

How much sleep should I get?

Average Sleep Needs
Age	Hours
0-2 months	12-18
3 months-1 year	14=15
1-3 years	12-14
3-5 years	11-13
5-12 years	10-11
12-18 years	8.5-10
18+ years	7.5-9