We all know getting eight hours of sleep is important. But while the sheer duration of sleep has been emphasized, not much attention has been placed on the timing of those eight hours.
Clearly, sleeping from 10 pm to 6 am is different than sleeping from 2 am to 10 am. They’re both eight hours, but one is much more rejuvenating. Instead of focusing on duration, the better approach would be to focus on the optimal bedtime.
Once the optimal time is determined, we can easily figure out duration: go to bed at that time, sleep for however long you need, and wake up naturally. Repeat this a few times to get an estimate of your sleep duration and set an alarm accordingly.
In finding this optimal bedtime, we’ll look at three traditional sources that have sustained humans for millenniums.
1. Traditional Chinese Medicine
The body clock is core to TCM and provides guidance on sleep. In particular, 11 pm to 1 am is the time of the gallbladder. 1 am to 3 am is the time of the liver. And 3 am to 5 am is the time of the lungs. All these times are periods of deep regeneration, so it’s recommended to be asleep before 11 pm and get up no earlier than 5 am.
Before 11 pm is the time of the triple heater (9 pm to 11 pm). It’s during this time TCM recommends that you should be falling asleep. Getting in bed by 10 pm or earlier seems to be the general recommendation. You’ll be sound asleep by 11 pm, just in time for the deep healing that occurs during then.
2. Ayurveda
Ayurveda (traditional Indian medicine) also prescribes a body clock that governs our physiology. 10 pm to 2 am is Pitta time, a period of enhanced healing. 2 am to 6 am is Vata time, a period of natural lightness.
The recommendation is to be asleep by 10 pm and to get up by 6 am. Getting in bed by 9 pm or earlier seems to align with the Ayurveda clock, as you’ll be in deep sleep by 10 pm, a time of regeneration.
3. Hunter-Gatherer Tribes
The sleep patterns of the Hadza, San, and Tsimane tribes were analyzed in this study. Tribespeople woke up when the temperature reached its lowest point (just before sunrise) and went to bed 2.5 to 4.4 hours after sunset.
With the change in sunset times over the year, the average bedtime comes out to about 10 pm. So, it seems 10 pm suffices as an overall recommendation.
Individual Variation
Please take these guidelines with a grain of salt. There’s plenty of variation caused by factors like season and age. Optimal wintertime bedtimes will be earlier than optimal summertime bedtimes. Optimal adult bedtimes will be earlier than optimal teenager bedtimes. If you’re sick, a 7 pm bedtime may be perfect. Find what works for you.
Your body and energy levels are the best indicators of when to go to bed. Never force yourself to go to bed when you’re not tired. That said, a 1 am bedtime is clearly not healthy. If you’re used to going to bed in the wee hours of the night, try adjusting your bedtime slowly.
Nowadays, you may not feel sleepy when you should be feeling sleepy. A lack of sunshine, overexposure to blue light, and a sedentary lifestyle can cause your body’s internal clock to lose sync. That’s where these recommendations come in handy.
If you’re ever in doubt, remember this old adage: “one hour's sleep before midnight is worth two after." Sleep as early as your body allows, which will generally be in the 9 pm to 10 pm range. Go even earlier if you want, but never later. Sweet dreams!