Circadiun rhythm.
Our bodies have a natural rhythm, a twenty-four hour clock, managing our sleeping patterns. It's twenty four and a quarter hours in reality, the sun or light resets the biological clock to twenty four hours daily. The rhythm should make you feel alert, or lethargic, awake or tired, twice daily. This internal clock is unique, indicating with regularity, when you should be awake or asleep. The rhythm being produced by the brain is communicated to every part of the brain and body. It aslo influences eating patterns, mood and emotions, metabolic rate and hormone release.
Melotonin.
Melatonin instructs the body and brain that it's time to sleep. This begins a few hours after dusk, when the brain detects it's getting dark. For a healthy human it has little effect on actual sleep, there are other processes and parts of the brain that ensure you get quality sleep. Studies have shown that there is a placebo effect when taking a melatonin tablet to aid in sleep.
Blue light.
We spend so much time these days, starting into our phones, or screens of some sort. Aritificial electric light, including fluorescent and LED light, also helps distrupt our body's natural ability to make us tired. Being able to control light, just by flicking a swith, gives us control over the enviornment we live in. This is something the sun and natural light used to govern, day and night. Where our body produces melotonin a few hours after dusk, electric light fools our system into believing the sun hasn't set, it's not time to release it.
With a lack of melotonin, our body doesn't prepare us for sleep. When we turn out the light, getting into bed, our body must catch up releasing melatonin.
Portable devices which use blue light LED's . Emit a level of light on the exact short wavelength that our eyes receptors use to transmit daylight signals to our brain. This has twice the effect old style yellow bulbs had on the production of melatonin.
Devices and reading.
Reading a book on an electronic device, our phone or tablet, as opposed to reading a book, also causes issues with sleep. An early study showed, doing this up to two hours before bed, blocked melatonin levels by up to 23%. A further study indicated, reading a book for five nights on a tablet as opposed to a book, over the same period. With randomised variables not affect the results of the study and no use of any blue light devices for email etc. Suppressed melotonin release by 50% or more, translating into a delay of over three hours. The instruction to sleep not being executed uthe early hours of the morning.
Alcohol the sedative.
Where earlier studies have shown alcohol allows us to fall into a deep sleep, later studies show it acts like more of a sedative. This means we aren't getting natural sleep; the alcohol knocks out our cortex. Due to the alcohol in our system, we are likely to wake up frequently during the night, which we can be unaware of. What it also doesn't allow is a useful amount of rapid eye movement sleep (REM). Drinking before bed, importantly the more you drink before bed, further pronounces this. This is important for our emotional and mental health.
Friday drink.
Missing out on REM, our brain makes a log of it, when we get the opportunity to sleep without our aid. We experience a REM sleep rebound; we achieve a normal level of REM plus our brain attempts to claw back the lost sleep. Causing us to dream more vividly, this happens acutely when we've had a good drink after work on a Friday, our body's saturated with alcohol. Which after a few hours, the liver and kidneys eliminates, we then experience crazy dreams.
Deficit.
When we have a deficit of REM sleep over a prolonged period, caused by the intake of alcohol. If we abruptly stop consuming, we experience the DT's (Delirium tremens), which I mentioned earlier are a build-up of this. Our brain will take back the REM sleep during the day when we are fully conscious. It's an extremely frightening experience.
It is exceptionally dangerous to stop drinking without professional help, consult your doctor before taking any action about your level of alcohol consumption.
Hotels and Jetlag.
Our brain resists deep sleep, the restorative sleep, which is good for our cardiovascular system and our metabolism, when we are not sleeping in what it believes is a safe environment. This evolutionary, our brain remains more alert, on guard. We don't feel rested when we sleep in hotel rooms, for instance.
Our ability to be in another time zone, faster than our bodies circadium rhythm can deal with, has caused another issue. We now experience a biological time lag, our body finds difficult to cope with. When it's daytime in the place we are currently in, our body believes it is still night-time. Obviously this happens in reverse when we make the return journey. When we want to sleep, our body doesn't rquire any, and so is wide awake. With it taking sunlight to readjust our internal clock, which is what normally happens, we are only able to recalibrate, one hour per day.
Caffeine
Adenosine works through the day, registering how long we've been awake. While the level of the chemical is rising, it's creating sleep pressure. Sleep pressure increases our desire to sleep. Eventually we will ave the urge to sleep, this normally occurs between twelve and sixteen hours every day. This is dependant on a healthy circadiun rhythm.
Caffeine makes you feel more alert and awake; it also fights adenosine to latch onto receptors in our brain and body. Once caffeine has attached it self, adenosine cannot. The process of building sleep pressure has been interupted. You now believe you are more awake, because of the caffeine.
Where the peak level of caffeine in your system occurs in around thirty minutes, the half-life, (our body's ability to remove half the concentration of a substance) of caffeine on average is five to seven hours. If we have a late cup of coffee, half of it will be activein our system five to seven hours later.
N.B. We are all different, caffeine sensitivity with any individual can be dependant on age, quantity, medication, enzymes in our liver and quality of prior sleep.
Crash.
Most of us that drink coffee, have experienced a caffeine crash. Energy levels drop dramatically, making it difficult making it difficult to function and you feel like sleep. While caffeine has been blocking adenosine attaching itself to the receptors, it has still been building up, the process didn't stop. When our body finally eliminates the caffeine residue, the adenosine atteaches itself to the receptors in much larger quantities.
Morning lark.
Some people prefer the morning, being more productive and comfortable, at that time of day. They're less productive later in the day, becoming comfortable with settling down and going to bed earlier.
Night owl.
Other people are more comfortable later in the day, preffering to be awake later and going to bed later. A night owl finds it difficult, if not impossible to sleep early, going to bed later means, to get the required amount of healthy, restful sleep. The owl needs to wake up and get out of bed later.
When we are this type, not getting enough sleep now means, we aren't going to function properly early the next morning. Where we look fully awake, our brain, particulary the prefrontal cortex (the boss) is likely to be in a state of sleep. This makes it difficult to engage our higher end thought processes, and logical reasoning.
Neither.
Of course, some people may be neither of the above. They are somewhere between the two types, with a slight leaning toward the evening. Knowing what type we are gives us more understanding of when it would be beneficial for us to sleep. Also why we feel the way we do during the day, changing our behaviour to accomodate which type we are is the best course of action.