How much sleep do I need?
The CDC recommends that adults get 7 to 9 hours of sleep each night to maintain their health and wellbeing. For children, the amount of sleep they need will vary as they age. Below, we outline the hours of rest required for each age group.
- Newborns (0-3 months): 14 to 17 hours
- Infants (4-12 months): 12 to 16 hours (including naps)
- Toddler (1-2 years): 11-14 hours (including naps)
- Preschool (3-5 years): 10-13 hours (including naps)
- School-age (6-12 years): 9-12 hours
- Teen (13-18 years): 8-10 hours
- Adult (18-65+ years): 7 or more hours
What is a sleep cycle?
We need at least 7 to 8 hours of sleep every night because this length of time allows us to experience 4 to 5 full sleep cycles. One sleep cycle lasts about 90 to 110 minutes and during it, we experience non-rapid movement sleep (NREM) and rapid eye movement sleep (REM). Both NREM and REM sleep are needed for proper physical and mental health.
What are the stages of sleep?
There are four stages of sleep—NREM stages 1, 2, & 3, and REM sleep. Each stage carries out essential functions needed to keep us healthy, active, and mentally alert.
The four stages of sleep are not necessarily linear. For example, REM sleep can occur at any time during the sleep cycle, and each cycle will not always start at stage 1. Stage 3 may also not automatically transition into REM sleep.
In most cases, the first sleep cycle of the night will begin in stage 1. Then, we progress through stages 1, 2, and 3, and into REM sleep. REM sleep typically begins 90 minutes after falling asleep. After the first REM stage is complete, the next sleep cycle could begin at either stage 1 or 2. In the remaining sleep cycles, REM may occur intermittently throughout and gradually become longer with each new cycle. The shift between each stage is mainly due to specific hormonal and environmental signals.
Below, we outline the effects and typical duration of each sleep stage.
NREM Stage 1 (5 to 10 minutes)
Stage 1 is often called “light sleep” because you are still somewhat aware of your surroundings as you drift off to sleep. Alpha brain waves begin in this stage and cause strange sensations, such as falling.
Brain activity and eye movement slow in stage 1, and muscles begin to relax. As tension releases from the body, sleepers may experience hypnic jerks—short muscle spasms or twitching.
NREM Stage 2 (30 to 60 minutes)
During stage 2, sleepers become less aware of their surroundings as theta brainwaves induce deep sleep. The body temperature and heart rate drop and muscles relax even further.
Burst brain waves called sleep spindles create a rhythmic activity in the mind. This rhythm reduces external stimulation, so deep sleep can take place. K-complexes also help reduce impressions of light, noise, and movement near the sleeper.
NREM Stage 3 (20 to 40 minutes)
Stage 3, also known as “deep sleep” or “slow-wave sleep,” is the most restorative stage. Slow delta waves begin to clean the brain, and Human Growth Hormone (HGH) works to rebuild muscle tissue. Important information is also consolidated and moved from short-term memory to long-term memory.
Physically, the body is slack and immobile, with minimal eye movement. Breathing rates and blood pressure are low, and sleep disruptions become less frequent while in deep sleep. The more time spent in stage 3, the more the need for sleep will decrease. For example, if your afternoon nap is long enough to reach stage 3, you may have a difficult time getting to sleep at night. If your body has already experienced enough restorative sleep, you will feel well-rested and less likely to fall asleep quickly.
It is also difficult to wake someone during stage 3, and sleepwalking, sleep-talking, and bedwetting tend to occur during this stage.
REM Sleep: 10 minutes
During REM sleep, also referred to as “paradoxical sleep,” brain activity increases while the muscles become paralyzed. Low amplitude brain waves cause the eyes to move in a quick side to side motion, while breathing becomes faster, irregular, and more shallow. Your body temperature also drops to its lowest point during REM sleep.
Vivid dreams often take place in REM sleep due to the increase in brain activity. However, muscle paralysis keeps us from acting out these dreams. The slackness of the body can also cause certain sleep disorders, such as sleep apnea, to become worse. Relaxed muscles can put pressure on the airways, obstructing breathing.
What is the circadian rhythm?
The circadian rhythm helps regulate your internal clock—the times of day you feel sleepy versus alert. This rhythm signals certain hormonal cues that tell the body whether it is time to sleep or be active. These hormonal signals are triggered by the environment, specifically, the rising and setting of the sun.
When the sun is up, and we are exposed to light, the body inhibits melatonin production (the sleep hormone). While reducing melatonin, the body increases other hormones that keep us awake and focused, such as cortisol and adrenaline. When the sun sets and light decreases, the body triggers melatonin production, and we become tired and more prone to sleep.
Hormonal signals from the circadian rhythm also help regulate the shift between NREM and REM sleep during each sleep cycle. By linking your sleep with your natural circadian rhythm, you will be more likely to spend adequate time in each of the four sleep stages.
When we experience jet lag, it is due to an absence or disruption of environmental triggers that signal hormone production, causing the sleep cycle to become out of sync with the circadian rhythm.
How can I fix my sleep schedule?
If your circadian rhythm or internal clock becomes disrupted, you may experience a hormonal imbalance. This imbalance can lead to higher than normal stress levels and further sleep issues.
The best way to regulate this cycle and get your sleep back on track is to go to bed and wake up at the same time each day. A set sleep schedule will train your body to feel tired around the same time every night—making it easier for you to fall asleep and get a full 7 to 8 hours of rest. Our sleep calculator can help you determine the best bedtime to ensure optimal sleep.
On the weekends, try only to adjust this schedule by one hour. The consistency will keep your internal clock in sync with your circadian rhythm, so you experience the benefits of each sleep cycle.
8 tips for a better night’s sleep
A consistent sleep schedule is the best way to keep your circadian rhythm intact and prevent any bouts of insomnia or sleep deprivation. However, you can add a few more steps to your daily and nightly routine to ensure proper rest.
Below, we include our 8 tips for a better night’s sleep.
1. Exercise Regularly
Studies show that 30 to 40 minutes of moderate physical activity a day can help you fall asleep faster and sleep soundly. Be sure to work out at least 4 hours before bedtime. The endorphins released during exercise can keep the mind active and make it difficult to sleep.
2. Avoid caffeinated drinks after 2 pm
A cup of coffee in the morning won’t harm your sleep cycle. But, consuming caffeine late in the afternoon could make sleep difficult to come by. Caffeine can stay in the body for up to 6 hours, so it is best to avoid any caffeinated drinks after 2 pm.
3. Eat smaller meals before bed
When the body is working to digest food, it can be difficult to relax and fall asleep. Therefore, it is best to avoid large meals 2 to 3 hours before bed. A light snack such as a banana or some almonds before bed can actually help improve sleep. For the best nighttime snack suggestions, be sure to read our article on 8 foods that promote better sleep.
4. Keep your bedroom dark
Excessive light can make it difficult to fall asleep or cause nighttime interruptions. Before bed, try to eliminate any sources of light—this includes light from electronic sources such as the television or alarm clock. To prevent outside light from getting into the room, consider blackout curtains or blinds.
5. Sleep cool
Overheating is one of the most common causes of sleep disruption. To avoid waking up sweating, keep your bedroom at a cool 65 to 72 degrees Fahrenheit. Also, be sure to select bedding and pajamas that are both comfortable and breathable.
6. Rest on a comfortable mattress
Sleeping on a lumpy mattress will cause you to sleep in uncomfortable and awkward sleep positions that leave your sore in the morning. Plus, when you are unsupported, you will be more likely to wake in the middle of the night and disrupt precious hours of sleep.
To prevent this, be sure you are sleeping on a mattress suited to your body type and sleep position. Mattresses are not one size fits all. What is supportive for a side sleeper, may not be right for a stomach sleeper. When you’re ready to shop for a new mattress, check out our review of the best mattresses of 2021. This article also includes a helpful buying guide that will make the selection process easy and straightforward.
7. De-stress before bed
When you climb into bed at the end of the day, stress and worry can often keep your mind active and prevent sleep. To ensure that you fall asleep quickly, try to alleviate stress and anxiety before bed. Stress relief can be done by writing out a list of concerns for the next day. By placing your worries on paper, you can get them off your mind and get to sleep faster. You can also relax before bed with a gentle breathing exercise that calms the nervous system or with a warm bath or shower to relax the muscles.
8. Reduce blue light exposure
Blue light from our electronic screens can often mimic the effects of sunlight on the brain. This light tricks the body into thinking it is still daytime, which can slow the production of melatonin and inhibit sleep. To avoid this, be sure to avoid all electronic devices at least 1 hour before bed.
The Importance of Good Sleep
Without proper sleep, our physical and mental health will suffer. Adequate time in each of the four sleep stages is vital to muscle recovery, memory consolidation, and mental clarity. Sleep deprivation can make it difficult to make crucial decisions, be productive at work, and focus on necessary tasks. Plus, shortened or inconsistent sleep can cause elevated stress levels that make it harder for us to regulate our mood and behavior.
Sleep doesn’t just impact your short-term health; it affects your long-term health as well. Consistent sleep loss has been linked to higher rates of heart disease, obesity, type 2 diabetes, and certain forms of cancer. Even though we all lead busy lives, sleep should always be prioritized—planning your schedule around 7 to 9 hours of sleep and using a sleep calculator to determine good bed times and wake up times is a great way to ensure you’re getting the necessary Zzz’s.