An integral part of sleep is our circadian rhythm, which follows a 24-hour cycle and is found in the suprachiasmatic nucleus. The suprachiasmatic nucleus is part of the hypothalamus, or the section the brain that regulates biological states such as appetite and sleep.
Circadian rhythms, which are essentially your “sleep clock,” are physical, mental and behavioral changes — responding to light, darkness and melatonin. The clock mostly functions properly on its own, but may sometimes be affected by external events.
● Light: Light striking our eyes is almost guaranteed to reset our sleep cycle and/or wake us up. This is because our brains are cued that the day is beginning when the sun is up and tells us we should no longer be sleeping. Avoid electronics right before bed, like keeping the television on while you sleep, since your sleeping body registers this light much like it might the sun.
● Time: Reading clocks and keeping track of time puts a certain amount of tension on your mind to get to sleep at the “right time.” It’s the same sort of stress you might feel, no matter how subconsciously, when you are late to work in the morning or to pick up the kids from school in the afternoon.
● Darkness: The hypothalamus produces a surge of melatonin come nightfall — this hormone promotes sleepiness. This is why it is difficult for most people to stay up in the late hours of the night, despite their best efforts. Keeping the blinds cracked at night is a great way to have the light sneak in in the morning and help wake your brain up before your alarm clock goes off.
It is said that if you fall asleep in 5 minutes or less after laying your head down on your pillow, then you are sleep deprived. The ideal time it should take to fall asleep is anywhere between 10-15 minutes. Exhaustion should be felt rarely. It is best to be just tired enough to fall asleep in this amount of time.
During the night your body cycles through several different sleep cycles. If these cycles are interrupted, you could wake up feeling slow and sluggish.
N1: This is the lightest stage of sleep. It is characterized by muscles relaxing and body temperature dropping. The transition usually takes place for about 5 minutes. You can very easily be awoken from the lightest state.
On an EEG, which measures electrical activity in the brain, brain waves slow down to around 4-7 cycles per second –a pattern called “theta waves.”
N2: By this time, your heartbeat and breathing slow down dramatically. This stage can last anywhere from 10 to 25 minutes, but people spend half of the total time sleeping in this state.
EEG tests display waves called “K–complex.” K-complex helps suppress arousal in this stage of sleep so you are not easily awoken to think you are in danger simply by hearing the fan oscillate in your bedroom.
N3: This stage only deepens your response to the outside world. A growth hormone is also released during this stage to aid in rebuilding torn muscle and tissues. This is why it is very important to be able to reach this level of sleep.
EEG tests will show very slow, large brain waves that indicate pulse slowing and blood pressure dropping significantly. Your body is most cold during this stage, having you reach for the covers.
REM (or rapid eye movement): This stage is most commonly known and discussed because most people dream during REM. It is the deepest cycle and happens about 3 to 5 times a night, usually lasting 1.5 hours.
Most people wake up groggy or tired if they do not get enough REM sleep. Insomnia, stress, night shifts or being a nursing mother can affect the amount of REM sleep your body can get during the night.
If you’re not getting enough sleep, it can have a major impact on your brain during the rest of the day. Recent studies have shown that, though the average person sleeps seven hours a night, less than eight hours’ sleep can actually lower a person’s IQ the next day.
On top of that, disturbed sleep cycles can impair your memory, raise stress levels and even shrink the brain itself — loss of sleep can result in chronically raised levels of cortisol, which is also present in those who suffer severe depression and post-traumatic stress. High cortisol levels affect the temporal lobe, which in turn affects learning and memory.
It is best to stick to a regular sleep and wake cycle as best you can. If you have to alter your natural circadian rhythm –if you work a night shift, for instance, you should have exposure to bright lights during the night and wear sunglasses to and from work in order to “trick” your body into changing the cycle. After a week or so of sticking to the same schedule, your body should adapt to the new schedule as if you were working regular 9-to-5 hours.
Unfortunately, issues concerning sleep trouble at least 70 million Americans –of all ages. This is why it is important to learn about sleep cycles and the best ways to avoid disrupting your night’s rest. Our bodies are basically forcing us to rest every night and it is best if we follow these signals accordingly.
Marcela De Vivo is a freelance writer in the Los Angeles area and founder of Gryffin Media. She currently works with MyWaterbedShop and writes on a variety of health and wellness topics. Check out more of her writing at her blog.