Sleep - Overview: Nursing

Sleep is a basic human need that allows for the proper functioning of the body and mind. A lack of sleep can cause patients to develop chronic health conditions, like diabetes, obesity, and depression, and impair daily mental and physical functioning. Let’s review the rhythm,  cycles, and physiology of sleep.

Now, the central nervous system integrates sleep using various parts of the brain, including the hypothalamus, which controls the circadian rhythm, the 24-hour sleep-wake cycle that includes a predictable pattern of physical, mental, and behavioral processes such as variations in body temperature, heart rate, blood pressure, hormone secretion, eating habits, and mood.

The hypothalamus controls the circadian rhythm and can be impacted by the amount of environmental light and other factors, such as noise, pain, and illness. 

Now, there are two main phases of sleep: non-rapid eye movement, or NREM, and rapid eye movement, or REM. These phases typically occur in 90 minutes intervals, with a normal sleep pattern containing 3 to 5 cycles total. Now, we spend the most time in NREM, which has three stages, called NREM 1, 2, and 3, which progress from the lightest sleep to the deepest sleep, whereas REM only has one stage characterized by lucid dreams and rapid eye movements.

Now, several physiological changes occur during sleep, including a decrease in heart rate, blood pressure, body temperature, respiration, and muscle tone. 

These changes occur because several central nervous system structures, hormones, and neurotransmitters work together to promote and regulate sleep. Starting with the hypothalamus, this structure controls the circadian rhythm and initiates sleep by secreting the neurotransmitter gamma-aminobutyric acid, or GABA. It also works with the brain stem to reduce activity in arousal centers and relax the body during sleep. Next, the pineal gland secures the hormone melatonin in response to decreased light to help regulate the sleep cycle. Lastly, the basal forebrain releases adenosine and acetylcholine to promote REM sleep.