Sleep Functions and Patterns

Functions of Sleep

• Boosting immune system
• Strengthening emotional processing
• Improving mood and decreasing stress
• Improving memory function
• Improving cellular growth
• Repairing tissue and muscle recovery
• Increasing productivity
• Improving exercise performance

Normal Sleep Patterns & Requirements

Newborns

• Sleep for 12-18 hours a day with an irregular schedule
• Enter REM sleep immediately, with body movement and irregular respirations
• Spend 50% of time in sleep only, with a 50-minute sleep cycle

Infants

• Awaken every 3-4 hours, eat, and then return to sleep
• Wakefulness increases during the first month
• By the end of the first year, take 2 naps per day and sleep for 9-12 hours
• Spend sleep time in light sleep with some activity, movement, gurgling, and coughing

Toddlers

• Need 12-14 hours of sleep per day
• Still need afternoon naps, but mid-morning naps gradually decrease
• Often resist bedtime and may awaken during the night
• Nightmares are common, and using a blanked or stuffed animal can help
• Maintaining a daily sleep schedule helps good sleep habits

Preschoolers

• Need 11-13 hours of sleep per night
• Resist bedtime due to wanting to play, watch TV, or engage in other activities
• Parents can help by maintaining a regular and consistent sleep schedule
• Frequently wake up at night, may experience night terrors or nightmares
• Limiting or eliminating TV can reduce nightmares

School-age Children

• Need 10-11 hours of sleep per night
• Often get less sleep due to homework, sports, social activities, and screen time
• Parents can help by maintaining a regular sleep schedule and limiting screen time

Adolescents

• Need 9-10 hours of sleep per night
• Often sleepy during the day, especially in school and at home
• Circadian rhythms tend to shift, leading to later sleep and wake patterns
• Use of the internet, watching TV, and cell phone usage disrupts sleep due to blue-spectrum light exposure
• Boys experience nocturnal emissions (wet dreams) and need to know it's normal

Adults

• Need 7-8 hours of sleep per night, but some can function well on less sleep
• REM sleep recurs every 90 minutes and lasts 5-30 minutes
• Brain activity is high during REM sleep, similar to when awake
• Dreams occur but are not remembered
• Paradoxical sleep, muscle tone decreases, and heart rate becomes irregular

Sleep Cycles

• Pass through NREM and REM sleep
• Complete cycle lasts 90-110 minutes in adults
• Sleeper passes through the first two stages of NREM sleep in 20-30 minutes
• Stage 3 of NREM sleep lasts 50-60 minutes
• After stage 3, the sleeper passes back through stage 2 and 1, then enters REM sleep
• Adult usually completes 4-6 cycles during a 7-8 hour sleep
• Sleeper awakened during any stage must begin a new cycle at stage 1 NREM sleep

NREM Sleep

• Occurs when activity in the ARS is inhibited
• Occurs mostly during the night
• Three stages:

Stage 1

• Light sleep, a few minutes, feeling drowsy and relaxed
• Eyes roll from side to side, heart and respiratory rates drop slightly
• Can be readily awakened and may deny being asleep
• Low voltage brain wave

Stage 2

• Sleep during which body processes slow down
• Eyes generally still, heart and respiratory rates decrease slightly, body temperature falls
• Requires more intense stimuli than stage 1: touching or shaking

Stage 3

• Deepest stage of sleep
• Heart and respiratory rates drop 20%-30%
• Sleeper is difficult to arouse
• Not disturbed by sensory stimuli, skeletal muscles very relaxed, reflexes diminished, snoring occurs
• Essential for restoring energy and releasing important growth hormone

Physiological Changes during NREM Sleep

• Arterial blood pressure falls
• Pulse rate decreases
• Peripheral blood vessels dilate
• Cardiac output decreases
• Skeletal muscles relax
• Basal metabolic rate decreases 10%-30%
• Growth hormone levels peak
• Intracranial pressure decreases