Sleep Time


Melatonin is a hormone which regulates the circadian rhythm of several biological functions. It is of produced by your pineal glands, derived from serotonin neurotransmitter. This process does only occur in darkness, thus melatonin is produced mostly at night. Production arises during the evening, peaks in the middle of the night and quickly drops to a low amount by the very first exposure of day light.

Melatonin production cycle depends on sunlight that enters your eyes, thus it synchronizes your body with night-day cycle. However, this won´t work as it should if you expose your eyes to light every night, using artificial light sources, such as electrical light bulbs, computer, television, etc. That´s why so many people in the city still sleep many hours after the sunrise, when they should already have waked up naturally.

If cutting down all light sources at night is not an option, one may take melatonin pills at night to compensate for the melatonin production that this light is robing from your pineal glans. However, light therapy will be much more effective as an effort to regulate your circadian rhythm.

Sleep-awake myths

Some may judge that it is ok to sleep during the morning and wake up late, but they would think twice if they were aware of all other negative health effects artificial lights can produce. Truth is that the disruption and quality degradation of sleeping hours and of other biological processes makes you prone to a number of health conditions.

We tend to think that to wake up early we just need to set an alarm clock and force ourselves to stay awake from that time onwards, but that, alone, will only make you feel sick during the day. Analogously, some may try going to bed when your body is not ready to sleep, but that will only make you get stressed at the bed, and may cause temporary insomnia. You may then find out it´s so hard for them to fix your sleeping hours with this method.

Light therapy

Controlling how much light your eye is exposed, and when they are exposed, is the most effective way to take control over your sleep-awake cycle, gradually advancing or retard your internal clock a few minutes (or hours) each day. However, to get proper results, you need proper understanding of how your body reacts to light (or melatonin), depending on your internal clock´s time.

First, you must find out at what time your spontaneously get awake without any external influence (such as an alarm clock). Name it as your “start time”, the time when your internal clock starts ticking for that day. Now check the human PRC (phase response curve) graph displayed below, noting that your “start time” is when the lines start being plotted (not necessarily at morning).

The graph shows how effective can light and melatonin administration be in changing your “start time”, moving it forward or backward along the 24 hour cycle. For instance, note that in between 3 to 9 hours past your “start time”, the light won´t alter your “start time”, because it is expected by your body at that time. However, the presence of light right before you sleep is unexpected and will retard your internal clock, moving your “start time” forward, as your body will think that it´s day yet. On the other hand, the presence of lights a few hours before your “start time”, when you were supposed to sleep, will trick your body to think your body to think that the day has begun earlier, thus advancing your internal clock and moving your “start time” backward.

There are artificial lights for that purpose, which are usually blue. However, a concentrated light source is very annoying and not very effective, as total luminance will be very low compared to day light. Most powerful choice is to do, at the right time, an outdoor activity, such as exercising, buy something or tidy up the yard. Alternatively, you may do an indoor activity, such as checking of your emails, or washing dishes, in a way that position where sun light from a window is reaching your eyes.

As illustrated below, a special setup with big mirrors or any other reflective material may be useful in this case:

Sun Light TherapyNote: The goal is not to reflect the sun image right into your eye, but just the image of an illuminated sky (either bluish or cloudy).

Internal clock manipulation

This is how to advance your internal clock efficiently, in order to sleep and wake up earlier, moving your “start time” backward:

  • As soon as you awake, get your eyes exposed to sun light. Effectiveness of this will only last up to 3 hours past your “start time”.
  • Wake up earlier and use the item above. This will maximize it´s effect by waking up earlier. But never awake up more than 4 hours earlier than your “start time”.
  • Nine hours after your “start time” (that´s usually at night), minimize the amount of light you expose your eyes to, so your body can start melatonin production.
  • If you wish to use Melatonin pills, use them only 6 to 12 hours after your “start time”. Don´t take Melatonin past the usual time in which you have been going to sleep, otherwise the Melatonin will make you sleep even latter.

Those who spend too much time using computers or watching TV at night may find it too hard to advance your internal clock a couple of hours. In this case, it may be easier instead to retard your internal clock in many hours, turning nights a couple of times, until your internal clock synchronizes with the day time of the next day. However, this is very exhausting, unless you are into something that is exiting you enough to suppress your sleep.

Now this is how you retard your internal clock efficiently, in order to sleep and wake up latter, moving your “start time” forward:

  • Make sure no day light will enter your sleeping room, so you can sleep and wake up in darkness.
  • You don´t need to force yourself into sleeping longer than your body asks for. Just try to remain in darkness for the first 3 hours past your “start time”. This will allow your body to continue producing melatonin for a longer time.
  • Nine hours after your “start time” (that´s usually at night), expose your eyes to light (do your light therapy). Keep on lights until you sleep. However, if you are late sleeping this day, shut off all light sources 4 hours before your “start time”.
  • If you wish to use Melatonin, take it as soon as you awake, or take it in the middle of your normal sleeping hours, up to 7 hours before your “start time”.

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