Sleep…We all need it, some need a lot of it, some need very little, some may be falling asleep while reading this. It alludes many while others never have a problem falling or staying asleep. It’s a complicated subject and not thoroughly understood by scientists. It can be broken down into two main parts; non-REM and REM. REM stands for rapid eye movement and happens at the end of the sleep cycles. The sleep cycles are numbered non-REM 1, non-REM 2 and non-REM 3, with REM always following the third non-REM cycle. The reason knowing these cycles is important because sleep affects all aspects of our life; energy, mental clarity, healing, immune functions, libido and many more. I will try to keep this complicated subject as simple as possible while attempting to make my point on why this is my number one factor in the aging process.
Non-REM 1 – The stage between wakefulness and sleep accounts for only 5% of our sleep cycle. It’s the stage where our muscles are still fully active, eyes roll, breathing slows and brain waves start to slow. During this short period of very light, easily disrupted sleep, usually lasting less than 10 minutes, the sleeper may be aware of sounds and conversations, but feels unwilling, rather than unable, to respond to them. A person awakened during this period will often believe they have never slept at all.
Non-REM 2 – the first unequivocal stage of sleep, during which muscle activity decreases still further and conscious awareness of the outside world begins to fade completely. If any sounds are heard, the sleeper is not able to understand their content at this point. This stage aids in sleep-based memory consolidation and information processing. Because sleepers pass through this stage several times during the night, more time is spent in stage 2 than in any other single stage, and it typically constitutes about 45%-50% of total sleep for adults.
Non-REM 3 – also known as deep or delta sleep and during this period the sleeper is even less responsive to the outside environment, essentially cut off from the world and unaware of any sounds or other stimuli. Stage 3 sleep occurs in longer periods during the first half of the night, particularly during the first two sleep cycles and represents around 15%-20% of total adult sleep time. Dreaming is more common during this stage than in the other non-REM stages, but not as common (nor as vivid and memorable) as during REM sleep.
REM – occurs in cycles of about 90-120 minutes throughout the night, and it accounts for up to 20-25% of total sleep time in adult humans, although the proportion decreases with age (a newborn baby may spend 80% of total sleep time in REM stage). In particular, REM sleep dominates the latter half of the sleep period, especially the hours before waking, and the REM component of each sleep cycle typically increases as the night goes on. The brain’s oxygen consumption, reflecting its energy consumption, is also very high during this period, in fact often higher than when awake and working on a complex problem. The majority of dreams, certainly the most memorable and vivid dreams, occur during REM and it is thought that the muscular paralysis that accompanies it may be a built-in measure to protect us from self-damage which could occur while physically acting out these vivid REM dreams.
Sleep progresses from Non-REM stage 1, to stage 2, to stage 3, then to REM sleep, back to Non-REM stage 3, then to 2 and back to stage 1, a cycle that lasts roughly 90 minutes. A disruption in the natural progression, such as from alcohol consumption, sleep aides, such as ambien or antidepressants that increase serotonin all disrupt the transition from one stage to the next, leaving you “stuck” in a stage and failing to gain the restorative qualities of sleep. Sleep hygiene is a must if you want to take back you life and start living well, follow the link below to see a list of these “must do’s and don’ts.” We are all different but those that exercise daily generally sleep quite well, which leads us to our topic for March, exercise, an anti-aging power house!
Dr Scott & the PWC Team!