How Much Should I Be Sleeping?
How much should I be sleeping? This common but loaded question is one of the most searched on Google about sleep (yes I checked). So I figured I will go over some of the minutiae of how much we should be sleeping.
To answer this question most researchers have turned to pre-industrial cultures and groups to see what people did before we developed electricity and indoor lighting. What is seen is shocking. Most (not all because nothing is absolute) pre-industrial cultures practice what is known as biphasic sleep. This means they sleep one long bout at night, typically about 8 hours and then have a 30-60 minute nap in the afternoon. In these cultures, the timing does change with the sun, but the pattern remains pretty constant. This is the physiological origin for cultures like Spanish or Greek cultures that practice an afternoon nap. This is vastly different from what is seen in most other cultures of modern society where we sleep in one chunk at night that is typically shorter than 7 hours.
This inclination to take an afternoon nap is seen all too frequently in modern society as we often feel a dip in attention or alertness in the afternoon after our midday meal. Many of us reach for another cup of coffee or a double shot of espresso or a sweet treat to try to supplement our way out of what is really a signal from our body to rest.
Now if we are going to accept that most of us are going to sleep in only one chunk and our lives do not accommodate taking an afternoon nap, the question still remains how much do I need. Part of the answer lies in who that I is? Our sleep needs change over our lifespans.
In young children we see polyphasic sleep, meaning multiple sleep and wake cycles. This explains why they take multiple naps during the day with hopefully a longer sleep period at night. As they go through their first year of life, their bodies get better at hooking on to the light dark cycle of the sun which slowly helps them progress towards the biphasic (twice/2) cycle we see in 4 year olds with a long night time rest and one daytime nap (the pattern we probably should maintain all our lives but oh well). In total amount of sleep, infants should be getting around 14 hours of sleep and 5 year olds should be getting around 11-13 hours. In all children, there is a standard deviation of 2 hours meaning they could be 2 hours above or below these marks and still be considered normal.
As we progress into later childhood, ages 6-13, sleep requirements sit somewhere between 9-11 hours. As we progress into teenages, about 14 to 17, our sleep requirements stay similar, around 8-10 hours. However this is where we do see another distinct sleep change. As we enter adolescence, our sleep timing shifts in a rather dramatic way, meaning our physical biology changes to a point where we fall asleep later and want to sleep in longer. Enter the myth of the constant sleepy teenager. This happens as we force them to wake up early, before they are fully reseted. On average, teenagers will fall asleep about 2 hours later than they previously did, and will actually experience a spike in alertness around the time they used to fall asleep. If they fall asleep around 9 pm as a middle schooler, they will physically want to fall asleep closer to 11 pm. I want to stress again, this is a physiological change and has nothing to do with a child being lazy or unmotivated. So, if your child needs a full 10 hours of rest and they fall asleep around 11 pm, they will most likely sleep until 9 am. If they have been getting up early all week for something like school, they will most likely sleep in even later.
Once we get into adulthood, our physical sleep requirements sit around 7-9 hours. This does not change even into our more advanced years. Older adults often sleep less, not because they need less but because their body struggles to generate and maintain sleep.
Hopefully this gives a baseline of how much we should be sleeping and dispels some misconceptions around it. Next week we will be going over what a circadian rhythm is.
