The amount of time you spend in REM sleep matters for your physical and mental health.
Sleep is a major contributor to our daily mental states. Feeling easily irritated, overly emotional or unable to concentrate are common complaints when we don't get the sleep that we need.
Sleep experts have found many connections between our experience of REM stage sleep and mood disorders such as depression.
What is REM sleep?
REM sleep is a stage in our sleep cycle where there is Rapid Eye Movement (REM) and our brain activity is similar to when we are awake.
Normal REM usually happens within the first 90 minutes of sleep at the end of the sleep cycle, and occurs a few times a night as we cycle through the sleep stages. When REM is abnormal, this stage happens too early in the night, lasts for too long or doesn't last long enough.
People who have depression and mood disorders commonly experience REM sleep abnormalities and don't experience quality, restorative sleep.
Non-REM sleep (NREM) is broken down into 3 or 4 stages:
Stage One: This stage is the lightest of non-REM sleep, which happens when someone is falling asleep or has recently fallen asleep.
Stage Two: This stage brings slightly deeper sleep. Heart rate, body temperature and brain waves drop slightly. This is the ideal stage you would want to wake up in after a nap, before you enter into deeper sleep which could leave you feeling groggy.
Stage Three/Four: These are the most restorative stage of your deep sleep stages. It is usually very difficult to wake someone up who is in this stage. During this stage your heart rate, body temperature and brain waves drop to their slowest. This is the stage of sleep that is most important for your body and is associated with muscle and tissue repair, growth, immune function and energy levels. This is also the stage you need to experience in order to wake up feeling refreshed.
You may want to think of NREM sleep stages as being most helpful for the body, while REM sleep is most helpful for the brain. REM sleep is associated with dreaming, emotional regulation, learning and memory. Although, both NREM and REM are important for the mind and body!
Interestingly, as we age we also experience REM and sleep stage 'abnormalities' (although this is a normal part of the aging process). It becomes more difficult, as we get older, to experience the good quality sleep that we need for healthy brain and body functioning.
Lacking REM stage sleep has been connected to less ability to cope with challenges in life, migraines and putting on weight. When you don't experience enough REM you may feel groggy, less able to focus, and have difficulty with your memory.
Getting too much REM on the other hand can lead to feeling angry or irritable, and increasing symptoms of depression and/or anxiety.
REM and dreaming...
REM is often associated with dreaming, and when woken up during this stage of sleep people tend to recount vivid dreams.
Although their is no definitive answer on why we dream, some research shows that REM sleep and dreaming helps us to regulate our emotions. Through dreams, we may be able to process emotions we experienced during the day, or become prepared for upcoming emotional challenges.
This theory suggests that through the dreams we have during REM sleep, this leads us to wake up feeling clearer emotionally and more optimistic. When REM stages are abnormal, our lack of dreaming or over-active dreaming could be contributing to negative mental states and emotion.
However, this is only one theory of many. Other theory suggests dreams are simply the result of random electrical impulses in the brain, and therefore may not have any significant role on our mental states.
How to improve your REM sleep
While low-quality REM sleep may be part of aging or a part of our genetics, there are many things you can do to improve your sleep cycle:
Healthy eating and daily exercise
Creating a bed time routine to help your brain and body prepare for sleep
Giving yourself enough time (eg. getting into bed 7-9 hours before you need to wake up)
Avoiding screens, alcohol and eating meals right before going to bed
Reducing night-time waking by reducing light, noise and temperature
Seeking treatment for medical conditions such as sleep apnea or sleep disordered breathing
Seeking treatment for mental health such as depression or anxiety
Experiencing good sleep is incredibly important for our health and well-being. When we sleep well, we have more energy, better physical health and a more positive mood. We are able to think clearer and feel happier, which leads to many good things!
Sources:
Pesonen, A.-K., Gradisar, M., Kuula, L., Short, M., Merikanto, I., Tark, R., … Lahti, J. (2019). REM sleep fragmentation associated with depressive symptoms and genetic risk for depression in a community-based sample of adolescents. Journal of Affective Disorders, 245, 757–763. https://doi-org.proxy.lib.sfu.ca/10.1016/j.jad.2018.11.077