Why is it that some people can sleep for five hours and wake up rested, while others needs nine hours or more to function? Why does it take you hours to fall asleep, only to wake up every hour, while others sleep like a baby?
Sleep needs do vary widely – total hours required, optimal bedtimes, and ideal wakeup times – that are dictated by an individual’s physiology, genetics, exercise levels, diet, and age group. Even habits you formed as a child could be influencing why you lie awake staring at the ceiling. But whatever a person’s sleep needs are, getting adequate sleep is crucial for optimal daily functioning. With overpacked schedules, travel, and stress, most adults do not get the recommended eight hours of nightly sleep.
Sleep habits through your life
Throughout your stages of life, sleep plays an important role in growth and development, but it also mediates physical damage and restores energy and strength.
As a baby, you might have slept up to 18 hours a day, with shorter sleep cycles and more time in the REM stage. After a few months, REM sleep proportionally accounts for about 30 percent of a baby’s sleep time, and sleep cycles start to lengthen. It’s different for every baby, but after a few months, daytime becomes awake time, with a couple of naps scattered throughout the day. Physical and mental growth is prime in this stage of life. Therefore adequate sleep and nutrition are crucial.
At school age, 10-12 hours of sleep a night can help a child wake up well-rested, ready to cope, more attentive, cheerful, and equipped to learn. A consistent, early bedtime helps develop good habits that will carry through to later years. At this age, kids are still growing quickly, and sleep patterns can change with changes in activity, hormone levels, and eating habits.
As a teenager, bedtimes and wake times tend to shift toward 11 pm, and most start to experience social jetlag with inconsistent sleep patterns. Although teens still need sufficient sleep (up to10 hours), they average only 8.5 hours on a school night. This lack of sleep has been linked to changes in hormones, metabolism, and general health, and can be related to common age-related issues including acne/pimples, mood swings, and weight changes.
As a young adult (ages 18-29), sleep needs will start to become more consistent, although the average adult still requires at least eight hours each night. For many reasons, bedtime is shifted later, with this age group tending to have the latest bedtime of any group. And because this group typically has work responsibilities, the average young adult gets only six hours of sleep a night, working through the week completely sleep deprived. Somehow this group seems to get by, but these bad habits can catch up to them in the form of chronic illness later in life.
As a 30-plus year-old adult, the average sleep requirement is at least eight hours a day, but this group only averages seven. Not surprisingly, adults lose sleep on work nights and try to make up for it on weekends, which isn’t the best for our internal clocks.
Gender doesn’t play a role, because men and women report similar sleep time and quality.
In our elder years, we still need at least eight hours of sleep per night, but we tend to have shifting sleep patterns. Biological reasons and chronic conditions can cause worse sleep quality, commonly resulting in mid-day napping. Sleep disorders like insomnia and sleep apnea affect nearly half of adults older than 65 and are more common in women than men.1
What should normal sleep patterns look like?
Sleep has defined stages that can be evaluated at a sleep laboratory.
Stage one is light sleep, when you can be easily awakened. In this sleep stage you start nodding in and out, twitching, or waking with a start from that sudden feeling that you’re falling. Eventually, muscle activity starts to slow.
Stage two is when eye movement stops and brain waves fluctuate between slow and quick bursts, but you are still considered in a light sleep stage. Physically, your body is preparing for a longer sleep duration by decreasing heart rate and body temperature.
Stage three is the beginning of deep sleep, a time when you can experience sleepwalking, talking, or even bedwetting. Brain waves fluctuate between slow, longer waves and smaller, faster waves. This deep sleep is also associated with increased levels of growth hormone, which is made by the pituitary gland and is necessary for tissue regeneration and repair, metabolism, changes in body composition, and bone growth. Athletes and children spend proportionally more time in this stage compared to the others because of their immense need for cell restoration and repair from the stresses of exercise and rapid growth.
Stage four is a continuation of deep sleep with slow brain waves. If awakened from this stage, you can feel disoriented, groggy, or confused for a few minutes.
Stages one through four are considered non-REM sleep stages, and are the stages when the majority of body repair and regeneration occurs.
REM (rapid eye movement) sleep, sometimes called stage five, is sleep with the highest brain activity – when you’re dreaming. Your body doesn’t move and your closed eyes oscillate quickly from side to side. Brain activity is similar to when you’re awake. Soon after falling asleep, the REM stage is shorter, but as your night continues, REM stage lengthens. REM sleep is where most brain repair, restoration, and regeneration occurs. Your dreams may seem long and vivid, even though you are only in this stage for 90 minutes total a night, for a handful of minutes at a time. When you dream you may only remember parts of the dream or nothing at all.2
Many factors affect the progression through the stages of sleep. You can go from stage one through stage four, then go back before entering REM sleep. The five stages of sleep occur in order, and when you reach REM sleep, the cycle starts over. A full sleep cycle through the five stages takes about 80-120 minutes, and each stage lasts about 5-15 minutes, so you should experience four or five full cycles each night.
What does sleep do for you?
Consider your sleep as a daily tune-up for your brain and body, because it plays many important roles for both mental and physical health. While sleeping, your brain is cleaning up from today, and prepping for tomorrow. Science shows that the space between brain cells increases during sleep, giving the brain the ability to clear toxins. Your brain forms new pathways for memory and knowledge acquisition and consolidates the learnings you accumulated during the day; which is why, after a good night’s sleep, you have a greater attention span, make quicker decisions, and are more creative.
Physically, your body uses this time for organ repair – your heart, blood vessels, skeletal muscles, etc. While you’re sleeping, your body has the time to produce more white blood cells that are necessary to strengthen and maintain your immune system. Sleep can help control hormones related to hunger (ghrelin) and satiety (leptin), which can make you feel hungrier and consume more calories when you’re not well-rested.3 If you lack sleep, you can feel “tungry” (tired-hungry) or “hangry” (hungry-angry) more easily and attempt to satisfy cravings with excess sugar, caffeine, or other stimulants for quick energy.
Sleep also affects the way insulin is regulated in your body. Imbalances of insulin, ghrelin, leptin, and other hormones can impact metabolism, calorie consumption, and body weight,4 affecting many aspects of health, wellness, performance, and personality on a day-to-day basis.
Health risks associated with poor sleep
As much as 1-2 hours of sleep loss a night can affect you significantly. And sleep quality is just as important as sleep quantity. With appropriate sleep quality and at the right times for your internal clock, you can become more efficient at finishing tasks, have improved reaction times, and make fewer mistakes.
Physically, sleep deprivation – chronic sleep loss or poor quality sleep – is associated with increased levels of the stress hormone cortisol. Sleep deprivation is also linked to the decreased production of glycogen – the storage form of glucose used for energy for daily activities and exercise.
Mentally, sleep deprivation plays a big part in risk-taking behaviors, depression, emotional and coping issues, and the inability to solve problems. You also might notice more irritability and less sense of humor.
Not enough, inconsistent, and poor quality sleep are all linked to increased risk for chronic diseases, including diabetes, heart disease, obesity, and depression. Also, being tired increases your daily risk for mistakes, injury, or accidents – ranging from errors in work to traffic accidents.
What to do
Before bed tonight, start developing better habits to support the best sleep you can get. Over time, these small practices, combined with optimal nutrition, can make a big difference.
Turn off electronics.
Sometimes it isn’t enough to put cell phone on silent. Turn it over, or better yet, move it across the room. Avoid TV, tablets, computers, and other blue lights that stimulate your brain and emotions.
Clear your mind.
Write down what you need to do tomorrow, so you don’t stress that you will forget. Consider supplementation to support GABA levels – the neurotransmitter that decreases the brain's stress-related beta waves and increases the production of its alpha waves, creating a profound sense of physical relaxation while maintaining mental focus and supporting restful sleep.*
Take a bath or shower.
The warm water will help your body feel cooler after you’re done.
Spritz your room and sheets with the scent. Lavender has been linked to improvements in deep sleep by supporting a lower heart rate and blood pressure.
Adjust to a new schedule.
If you are off schedule, traveling, or need to start going to bed earlier, then support your internal clock. Melatonin exerts its sleep-promoting effect, decreasing the amount of time you need to fall asleep by promoting the ability to stay asleep and enhancing the depth of sleep.* The sooner you get on a new schedule, the better you will sleep, eat, and feel.
Optimize room conditions.
Keep your room temperature at a cool 60-67 degrees. Make the bed with clean sheets and a weighted blanket. White noise helps drown out sounds outside.
Feed your sleep.
Take a magnesium supplement before bed because it can relax muscles and support restful sleep.
- Watson N, Badr M, et al. Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion. Sleep 2015;38(8):1161-1183.
- Herlin B, Leu-Semenescu S, Chaumereuil C, Arnulf I. Evidence that non-dreamers do dream: a REM sleep behaviour disorder model. J Sleep Res 2015;24(6):602-609.
- Greer S, Goldstein A, Walker M. The impact of sleep deprivation on food desire in the human brain. Nat Commun 2013;4:2259.
- Kim T, Jeong J, Hong S. The impact of sleep and circadian disturbance on hormones and metabolism. Int J Endocrinol 2015;2015:591729.