Why is sleep vital to good health? The National Heart, Lung, and Blood Institute (NHLBI) explains that without enough quality sleep, our mental, work, and social capacity declines as our risk for chronic health issues, injury, and death increases.
A common problem in the U.S., below are highlights from the extensive NHLBI webpage “Sleep Deprivation and Deficiency.”*
Sleep, physical function, and well-being
Sleep rejuvenates the brain and body, helping them work properly during waking hours.
- For example, prolonged lack of sleep impairs healing of blood vessels which can increase the risk of heart disease; raises blood sugar above normal levels, potentially increasing diabetes risk; and it can compromise immunity.
- Sleep promotes new brain pathways that enable learning and memory, whereas inadequate sleep can lead to difficulty in decision making and problem solving, as well as emotional and behavioral instability.
- With the body and brain refreshed through adequate sleep, our overall performance and safety is enhanced.
How we fall asleep
We sleep via an internal “body clock” that typically tracks on a daily, repeating 24-hour pattern called a circadian rhythm. This rhythm governs when it is time for us to sleep and wake, and it affects every cell in our body.
Circadian rhythm is influenced by two factors:
- A pressure, or drive, to sleep builds throughout the day as levels of the chemical adenosine increase in the brain, peaking in the evening.
- Environmental cues such as darkness and light signal times for waking and sleeping in your internal body clock.
- Darkness signals production of melatonin hormone that prepares the body for sleep, while light signals cortisol hormone that wakes the body.
Once asleep, a healthy pattern involves three-five cycles of REM (rapid eye movement, where dreaming occurs) and non-REM (deep or slow wave sleep) each night.
Optimal amount and deficiency
Most adults (people aged 18 and older) need 7-8 hours of sleep each day. Anything less becomes your “sleep debt.”
- Sleep debt cannot effectively be compensated for through napping. While napping does give a temporal boost in alertness and function, it does not provide all the benefits of nighttime sleep.
- Extra sleep on weekends, though it may make you feel better, can interfere with your circadian rhythm and be a sign of sleep deprivation during weekdays.
- It is also essential that the time you sleep matches your circadian rhythm. Otherwise, you can still be deficient even after sleeping 8 hours (example, shift work).
- Likewise, caregivers can be sleep-deprived if they are routinely awakened.
- Because poor sleep habits can lead to long-term health issues, NHLBI advises identifying problematic sleep patterns with a sleep diary.
- Symptoms of sleep deficiency include feeling very tired during waking hours, not feeling refreshed after sleeping, and having reduced daytime capacity.
- Besides shift workers and caregivers, another group at higher risk for sleep disorders is those with medical conditions such as heart disease, high blood pressure, obesity, and IPF.
Example strategies for better sleep
- Allow enough hours in the evening for adequate sleep.
- Sleep during the same time frame each day.
- Limit extra sleep on non-working days to no more than an hour.
- Nap for no more than 20 minutes.
- Avoid heavy exercise and computer/smartphone/TV screens an hour before sleeping.
- Avoid heavy meals 2 hours before sleeping, as well as caffeine beyond mid-afternoon.
- Maintain a quiet, cool, and dark sleeping area.
Talking to your doctor
People who feel they may have a sleep disorder are encouraged to speak to their doctor.
Subjects to consider beforehand include:
- Length of time with the problem
- Daily time frame for sleeping
- Time needed to fall asleep, how often you may awake during the night, and time needed to fall back to sleep
- Whether you snore
- How refreshed you feel upon waking and level of tiredness during the day
- Whether you fall asleep during routine activity such as driving (microsleep)
For more on sleep, see NHLBI’s “Your Guide to Healthy Sleep.”
*National Heart, Lung, and Blood Institute. Sleep Deprivation and Deficiency [Webpage].