Your sleep pattern is like a timepiece which your body uses to understand when it’s time to sleep and when its time to wake. This works alongside your body’s need to sleep which is governed by two factors:
How long you have been awake
The regular timing of your sleep
The timing of your sleep is controlled by something called the circadian body clock located in the depths of your brain. Once your body clock has decided it’s time to rest, it works with other functions in the body to help prepare you for the night of sleep ahead, stopping the various bodily functions associated with being awake. The same goes for when it’s time to wake, where the reverse happens.
You quickly develop a sleep wake cycle from birth. It’s guided by a number of cues to decide if the time is right for sleep. These include daylight, mealtimes and the regular timing of activities carried out at a certain times of the day.
Our bodies naturally adjust our sleep wake cycle to be in line with the day night cycle. This is down to a hormone called melatonin which naturally secretes itself in darkness to promote sleepiness and suppresses itself during daylight to keep you awake.
The invention of electric lighting has completely altered our natural sleep wake cycle. Instead of naturally falling asleep when it gets dark, we find ourselves staying up later and later due to the suppression of melatonin caused by the light. And with big screen TVs finding their way into our bedrooms, which are essentially big boxes of light, people are falling asleep much later.
The natural sleep wake cycle can demonstrated if you go camping. After a few nights in a tent without lighting, you often find yourself going to sleep earlier when the sun sets and getting up earlier in the morning at sunrise.
Interestingly, even most blind people are affected by daylight and melatonin since although they can’t actually see daylight, the connections from their eyes to their brain still exist to tell their brain if they’re in daylight or darkness.
Monophasic Sleep Pattern
Monophasic sleep is essentially what most people would call a normal sleeping pattern. A person sleeps for around 8 hours per night, variable per person. It’s the most common sleeping pattern and the one most societies have adopted. Nothing abnormal here.
Biphasic Sleep Pattern
Biphasic sleep is where a person sleeps twice per day. Most commonly, it consists of a long sleep during the night with a shorter rest during the day.
While not considered all that common in Britain or America, siestas, a short afternoon nap after lunch, are common in Spain and many Latin American counties.
The siesta takes advantage of what’s called the post lunch dip, a period in the early afternoon after lunch where your body feels a bit more sleepy than usual and can nod off more easily. Siestas are often no more than 30 minutes, any longer and you would go into a deeper stage of sleep which would be hard to wake up from. When done right, a short afternoon nap provides deep refreshment, and can actually have the same effect of a few extra hours sleep.
Alternatively some people adopt a biphasic sleep pattern by having a much longer nap of around 90 minutes. This works because it gives the body time to complete a full cycle of sleep so you would most likely be in either REM or NREM stage 1 so when it’s time to wake up you would feel naturally awake and refreshed.