Every night, nearly every person undergoes a remarkable change: we leave waking consciousness and for hours traverse a landscape of dreams and deep sleep. When we wake up, we do not remember anything about the hours that have just passed. There are many instances where we do not appreciate the benefits of sleep. All living beings exhibit regular, routine patterns of sleep and activity that are identical to the patterns seen in humans. Depending on changes in responsiveness and behavior, scientists have reported the following characteristics that define sleep:
- It is a period of reduced activity
- Sleep is normally associated with a single, comfortable posture such as lying down with eyes closed in humans
- It is defined by a decreased responsiveness to external stimuli
- Sleep is also defined as a state that is extremely easy to reverse (this distinguishes sleep from other states of reduced consciousness such as coma and hibernation)
From studies of behavioral changes that typically accompany sleep and simultaneous physiological changes, scientists now define sleep based on brain wave activity patterns and other physiological changes as mentioned below. Sleep is divided into two types: rapid eye movement (REM) and non-rapid eye movement (NREM or non-REM) sleep.
- Physiological Changes during Sleep
- Dreams
- Benefits of Sleep
- Hunger and Eating; Sleepiness and Sleep
- The Learning Process and Sleep
- The Impact of Sleep Deprivation on Learning and Performance
- Costly, Preventable Accidents
- Sleep Deprivation and Mental Performance
- Waking up to Sleep?
- Daytime Napping
- How Sleep is regulated
- Stable Wakefulness and Stable Sleep
- Factors That Influence Transitions
- Sleep Cycles
- Sleep Drive
- Awake and Sleep
- Sleep Drive and Body Clock throughout the Night
- A Delicate Balance
- Sleep in the Real World
- Effect of Light
- Melatonin
- Pain, Anxiety and Other Medical Conditions
- Medications and Other Substances
- Sleeping Environment
- Sleep Disorders
- Sleep Hygiene – The Healthy Habits of Good Sleep
