Sleep is one of our most precious health resources. Without it, not only does our quality of life decline sharply, but also we’re at a higher risk for a long list of poor health outcomes.
Both short- and long-term sleep deprivation can affect your brain so much that missing an entire night’s worth of sleep, or a week of 4-5 hours per night is the same as having a blood alcohol content of 0.1%! (1) (States impose criminal penalties for levels at 0.08 and above; Colorado does above 0.05%.) It’s no wonder that 20% of car accidents are related to sleep deprivation.(2)
Insomnia, or lack of sleep, includes problems falling asleep, waking frequently during the night, difficulty falling back asleep, or waking too early in the morning.
The average healthy adult needs 7-8 hours of sleep per night.(3)
Not getting enough sleep is a big deal! When a person doesn’t get enough, their heart rate and blood pressure will elevate, they will make more inflammatory chemicals in their body (c-reactive protein), have impaired glucose tolerance (inability to process blood sugar), increased appetite and weight gain, and poor immune system function.
The most shocking statistic around insomnia is that people who got less than 7 hours per night on a long-term basis had a greater risk of dying than those who didn’t! (4,5)
Americans have reported a decrease in average hours slept by one hour per night between 1959 and 1992. (6,7). A newer study in 2010 reported many people who slept less than 6 hours a night. (8). This overall decrease in sleep is blamed on a societal trend toward longer work and family hours that go with our modern lifestyles.
The American work ethic has created mile-long ‘To-Do’ lists and responsibilities that leave little time for sleep. It even seems that sleep is looked down upon and perceived as a weakness, as many people take the attitude that sleep wastes time and impedes our ability to finish our jam-packed task lists!
Sleep can be affected by eating late in the evening, and the type of foods eaten. As the our bodies are winding down preparing to rest, they are jolted back into working on digestion and not to mention the hormonal rollercoaster that blood sugar variations cause.
When a sugary meal is eaten, blood sugar and insulin rise in response. This can interfere with the body’s sleep process as it fights to regulate hormones associated with eating, rather than sleeping.
Ideally, a person shouldn’t eat after 7pm assuming they are going to sleep by 10pm. And we’ve mentioned before the “golden hours” of sleep occur between 10pm and 6am - more on this later! Other than disrupting sleep hormones, eating may predispose a person to acid reflux. Having a full stomach and lying down in bed is a common cause of acid reflux, as the stomach contents are more easily able to flow up the esophagus when a person is lying down.
Caffeine is of course a stimulant and hangs around in your body longer than you may think. The half-life of caffeine is approximately 5 to 7 hours, which means in that time, only half of the caffeine you ingested is out of your body.
Looked at another way, 75% of the caffeine you ingest will be gone 8-10 hours later.
Drinking caffeine later in the day (noon or later) means that a decent amount of it will still be in your body when you’re trying to sleep. If you have sleep issues, avoiding caffeine, even in the morning, is a good idea.
Alcohol is well known for its sedative properties. Drinking promotes relaxation and the onset of sleep. However, the side effects of alcohol on the sleep process aren’t worth its use as a sleep aid!
Studies have shown that even moderate alcohol consumption as long as 6 hours before bedtime caused reduced sleep efficiency (meaning the quality of sleep was poor), reduced periods of the most important types of sleep (REM sleep), and reduced total sleep time. Additionally, people who drank before sleeping woke up twice as often as people who didn’t drink.(9)
Because alcohol has long-term effects on sleep, people with any sort of sleep issues should avoid it.
It’s common for people to report they have a harder time falling asleep after they exercise in the evening.
Exercise doesn’t have to be vigorous for it to cause a release of the body’s stress and anti-inflammatory hormone cortisol, in addition to other stimulating hormones (epinephrine and norepinephrine) that are responsible for the exerciser’s “high”. This of course isn’t good if you’re trying to sleep!
Ideally, exercise should occur earlier in the day, so the cortisol and excitatory hormone release has time to wind down. On the other hand, more restorative exercise like yoga or stretching are better suited later in the evening as they can help lower stress hormones and relax your mind in preparation for sleep.
Last and perhaps most important, stress is a very common cause of insomnia. Both short-term and chronic stress can easily raise cortisol levels.
Cortisol is naturally highest in the morning, and normally lowers in the evening to allow for sleep.
Unresolved stress will keep cortisol high at night, impeding the sleep process. One of the biggest clues that a person has elevated night time cortisol is awakening around 3am and not being able to get back to sleep.
Keep in mind the best hours for sleep are from 10pm to 6am, or very close to that. This is when our bodies are most prepared for sleep, as our daily hormone rhythms change during these hours. Getting this same 8 hours of sleep, from say midnight to 8am, just isn’t the same. It will be a poorer quality, less restorative sleep. So do your best to sleep between 10pm and 6am!
1. Czeisler CA. Harv Bus Rev. 2006 Oct;84(10):53-9, 148.
2. Centers for Disease Control and Prevention (CDC). MMWR Morb Mortal Wkly Rep. 2012 Apr 27;61(16):281-5.
3. Online document at: http://www.sleepfoundation.org/article/white-papers/how-much-sleep-do-adults-need. Accessed October 20, 2015.
4. Gallicchio L, et al. J Sleep Res. 2009;18:148-58.
5. Hublin C, et al. Sleep. 2007;30(10):1245-53.
6. Kripke D, et al. Arch Gen Psychiat. 1979;36:103-16.
7. Bliwise DL, et al. Soc Sci Med. 1992;34(1):49-55.
8. Knutson KL, et al. Sleep. 2010;33:37-45.
9. Landolt HP, et al. J Clin Psychopharmacol. 1996 Dec;16(6):428-36.
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