Deep sleep is the third stage of non-rapid eye movement (non-REM) sleep when you are not dreaming. Deep sleep is also known as slow-wave sleep. This is the stage of sleep where your brain waves are at their slowest. Your heartbeat and breathing also slow down. This is when tissues repair and regrow. Your body strengthens its immune system, and builds bone and muscle. You need deep sleep.
Sleep experiments (some done in connection for torture and interrogation techniques!) show that if you let people sleep but monitored their brain waves and woke them whenever they dropped into deep or REM sleep, it led to psychological distress, even hallucinations. You need deep sleep and dream time.
My FitBit tells me how much deep sleep, light sleep, REM time, and time awake I get overnight. Most adults should aim for seven to nine hours of sleep each night, and most of us are sleep-deprived for a variety of reasons. I try for 7 hours but I have sleep apnea so my awake time is higher than it should be. Between 13-23% of your time should be spent in deep sleep. If you get seven hours of sleep each night, then you should spend approximately 55 to 97 minutes each night in deep sleep.
A few years ago when I got that sleep-tracking device I read that deep sleep appears to trigger a cleaning system in the brain. It is also believed that this deep sleep cleaning helps protect the brain against Alzheimer’s and other neurodegenerative diseases. So, I became a bit obsessive about how much deep sleep I was getting and how I might increase it.
Tracking those slow brain waves researchers found that these waves appear just before a pulse of fluid washes through the brain. That fluid (cerebrospinal fluid, or CSF) is the wash that presumably removes toxins associated with Alzheimer’s disease.
How do you get high-quality deep sleep? There are lots of answers and not one definitive answer. Lifestyle changes, like improving diet and exercise, can help but are never easy to implement. I’ve read a lot about sleep and have focused more on deep sleep and have tried a variety of things and recorded my times in the 3 stages and awakeness looking for what works for me.
The common list of things to try:
Daily workouts for about 150 minutes a week. It doesn’t have to be intense. Walking and some yoga is good.
Eat more fiber and have less caffeine and alcohol, particularly in the 7 hours prior to bedtime.
Make your bedroom conducive to sleep. 65-67 degrees, dark, with a TV or electronic devices and quiet. Darkness helps. An eye mask might work if it’s hard to blackout your room. Even if the mask falls off during the night, it can help you initially fall asleep. Some people find a white noise device blocks sound. Pink noise is those sounds like steady rainfall or waves crashing on a beach. There is some evidence that this increases deep sleep and improves memory in older adults.
Keep to a routine whenever possible about the time you go to bed. If you want 7 hours of sleep and have to get up at 7am, going to bed at midnight won’t accomplish that since some of that 7 hours will be awake time.
Over-the-counter sleep aids are big business from melatonin to valerian, kava kava and some antihistamines that cause drowsiness. Prescription sleep aids are also a big business.
What has worked for me?
The best thing is for me to get to bed earlier. 10 pm seems right, but certainly not midnight as I have often done in the past.
I have increased my fiber for other reasons and I don’t know if it has improved my sleep. I avoid alcohol and caffeine as it does negatively affect me.
Another thing my FitBit does is record steps and also active hours per day and week. I have found that on days when I really get in a lot of walking or exercise, I have not found significantly better sleep that night. I think the benefit may be cumulative rather than daily.
We have never had a TV in our bedroom, though I admit that I get sleepy watching TV. If I doze off on the couch watching TV and then head for the bedroom, the sleepiness disappears. Some nights I put my phone on that dark mode and will do one last check on email and such before I put my head on the pillow. I haven’t found that no phone before showed any improvement.
I have tried most of the sleep aids with mixed results. I don’t want to get into a habit of taking anything to sleep. Each thing I have tried seems to work sometimes and not work other times, so my conclusion is that a good night’s sleep is caused by other factors.
On a good night, my watch shows, for example, I slept for 7 hours and 25 minutes and 90 minutes was deep, 66 minutes awake (some of these are 1 or 2 minutes intervals that you don’t know you’re awake and some are fully awake and maybe walking to the bathroom or getting a drink of water) and also 83 minutes was REM dream time. If my deep and REM time are each greater than my awake time and I get 7+ hours total, I consider it a good night.
What works for you?