How much sleep is recommended?
- 7-8 hours/night. Sleep opportunity (the amount of time you are in bed) is most important – aim for 8 hours. However, sleep quality is also important, meaning that if you have trouble staying or falling asleep, or have a sleep disorder such as sleep apnea, getting adequate sleep opportunity is not sufficient.
How does lack of quality sleep affect our health?
- Increased risk of heart disease (45-400% increased risk in studies)
- Increased blood sugars (in one study participants slept 4 hours/night for a week and had 40% higher blood sugars after eating)
- Weight gain/difficulty losing weight (studies show that sleeping less than 7 hours per night induces more hunger and causes us to eat 200 more calories each day, which totals 70,000+ calories/year, enough to gain 10-15 lb/year)
- Reduced immune system (sleep deprived participants in a study were almost 3 times more likely to get a cold when exposed to the virus)
- Increased risk of cancers – breast, prostate, endometrium, and colon with as much as a 40% increased risk.
What affects our sleep and how can we modify our routines to help our sleep?
- Light exposure in the evening. While during the day, sunlight and other bright lights are important to help us know it is daytime and we should be awake, in the evening even a dimly lit living room which is only 1% as bright as sunlight can suppress our melatonin levels by 50%. Melatonin is the hormone that helps our body prepare to fall asleep. LED lights and electronic devices are particularly harmful to our sleep due to increased blue light exposure which potently suppresses melatonin release. Avoid LED lights and screens within an hour of bedtime. Consider using blue light filtering glasses or apps if you need to use devices. Reading in a dimly lit room, listening to music without lyrics, or meditating before bed can help with sleep (check out Calm, Headspace, or Insight Timer apps for help with meditation)
- The ideal sleep temperature is around 65 degrees but most of us keep our homes much warmer than this. Your core body temperature needs to drop about 3 degrees to fall asleep. It does this by losing heat primarily through the hands and feet. Having warm, well-circulated hands and feet is important, but the ambient room temperature overall should be cooler than most of us currently set it for. Set your thermostat lower at night.
- “I can’t turn my brain off.” In our fast-paced world there is a lot we have on our minds and many of us struggle with putting these things out of our minds at night. However, this is critical to falling asleep.
- Take the time to process your day and write down what you need to do tomorrow.
- Only go to bed when you’re tired and don’t lay in bed for more than 20 minutes, get up and read until you are tired and then go back to bed.
- Ask your doctor about CBT-I (cognitive behavior therapy for insomnia) which has strong evidence that it is effective for helping with difficulty sleeping.
- While alcohol can help you fall asleep, it is not a good quality sleep and would be better described as sedation or light anesthesia. It fragments sleep and limits our ability to get restorative deep/REM sleep. It is best to avoid alcohol altogether in the evening.
- Our natural inclination to be tired and want sleep is driven by the buildup of ADP in the brain. Caffeine blocks the receptors so that we sense less ADP and feel more awake. However, as caffeine wears off we are hit with the original amount of ADP we had plus all that has built up in the meantime which can make us exhausted. The half-life of caffeine is 5 hours, meaning that if you have two cups of coffee (16 oz, a typical serving) at 4PM this is like chugging one cup of coffee at 9PM since half of the caffeine is still in your system. This will greatly limit your ability to fall asleep. Limit caffeine to the early morning, certainly before noon.
- Circadian rhythm. Our internal clock or Circadian rhythm plays a huge role in our ability to fall asleep and get deep/restorative sleep. Staying up late one night or sleeping in late one day/week can significantly affect our rhythm and cause fatigue and difficulty sleeping thereafter. Probably the most important thing we can do other than allowing sufficient sleep opportunity is going to bed and getting up around the same time every day, even on the weekend.
- Sleep disorders. Sleep apnea is the most common sleep disorder and occurs due to airway collapse during the night during which period you stop breathing and develop low oxygen levels and increased carbon dioxide levels. The low oxygen levels disrupt the brain’s restorative sleep machinery and has negative cardiovascular implications as well (increased risk for heart disease). Signs of sleep apnea may include snoring, nighttime awakenings gasping for air, daytime fatigue, morning headaches, and high blood pressure. If you are feeling tired despite adequate sleep, you should have a sleep study and get treatment for sleep apnea if it is present.
For more information:
- Why We Sleep: Unlocking the Power of Sleep and Dreams by Matthew Walker PhD. Paper book or audio book.
- National Sleep Foundation: https://www.sleepfoundation.org/