There are a few threads on MAP with questions about sleep, so I thought I would give an explanation on what is going on during your sleep, how to get to sleep and why you may have sleep problems. Our ancestors were not governed by the alarm clock. They would have gone to bed when it was dark and got up when it was light. This influence of light and dark is linked to the movement of the planets and affects nearly all living creatures including plants, which open and close with the cycle of the sun. What causes us to wake when it is light? When light (from whatever source) hits our eyes or skin, the brain thinks it is morning. In response to this the hormonal system releases cortisol. This is the wake up hormone that says ‘get up, get ready and prepare for work’. For our ancestors this would have been’ get up and prepare for survival’ it is not any different for us today, we just perceive it differently. Cortisol levels rise at about 06.00am and peak about 09.00am, after which they drop slightly but remain high through lunch time so you can carry out your desired activity. Cortisol starts to drop in the afternoon when the sun starts to go down, which is when you reach for the coffee or energy drink (I will explain why that is not a good idea later). When cortisol decreases then melatonin levels start to rise. Melatonin is the sleep hormone (which promotes growth and repair).This is when we should follow our ancestors and start to prepare for sleep, which should ideally be around 10.00pm. The above pattern is known as the sleep/wake cycle, which can be seen in the illustration below. Why can I not sleep? There are many reasons why cortisol levels may remain high well into the evening and night. Your body releases cortisol in response to stress. The body does not know the difference between falling down the stairs, alcohol, coffee, light stimulation from televisions, computers, fluorescent lights etc. It is all just stress to the body, which responds by producing cortisol (wake up get ready to go). This would be a good thing if you was in a situation where you needed to needed to get a task done (such as driving to meet a loved one in danger,or fighting to survive), but not when trying to get to sleep. Cortisol can take hours to leave the bloodstream, which will inhibit the release of melatonin, this at night when you are trying to sleep, will cut into the body’s physical and psychological repair time, making you wake up tired and irritable. Let us take coffee as one example of a stimulant that will release cortisol. Caffeine has a half life of around 6 hours. So that coffee taken a 09.00pm will lead to half the caffeine still being in the blood at 03.00am. This is when you should be well into the psychological repair phase of your sleep. Therefore, it would be better to avoid stimulants of any kind after lunch. Remember stimulants will include light sources. Drinking water and remaining hydrated is very important, as dehydration is seen as stress by the body. Stress = release of stress hormones = wake up hormones. Entrainment Entrainment is defined as the tendency for two oscillating bodies to lock into phase so that they vibrate in harmony. It is also defined as a synchronization of two or more rhythmic cycles. The principle of entrainment is universal, appearing in chemistry, pharmacology, biology, medicine, psychology, sociology, astronomy, architecture and more. Christian Huygens a notable physicist coined the term entrainment after he noticed, in 1666, that two pendulum clocks had moved into the same swinging rhythm, so one clock had become entrained to the rhythm of the other. Subsequent experiments duplicated this process. How does this affect sleep patterns? Chances are during the day (and night) you will be exposed to low frequency electromagnetic energies. Power lines, electrical circuits in your walls, ceilings and floors and electrical appliances such as electric blankets and TV’s all emit such energies. This electromagnetic pollution can disrupt natural sleep / wake cycles. What to do Try unplugging all electrical items in your bedroom, including clocks, TV’s and lights. If your sleep quality improves, rearrange your bedroom so that all electrical items are as far away from your bed as possible. Also do not use an electric blanket. Other forms of entrainment Doctors and psychologists have discovered that you can become entrained or synchronized to a dysfunctional schedule in as little as 7-21 days. This means that if you stay up to midnight for one to three weeks in a row, your internal body clock will become entrained to wait until midnight to start reducing cortisol output and increasing melatonin output. If your body gets used to going to bed late and you then decide to get to bed earlier one night, you’ll probably have a hard time falling asleep. Now you are faced with the task of entraining your system to release your sleepy-time chemicals early enough so that you can get to sleep on time for a full cycle of physical and mental repair. In addition, if you work in an environment with other people, your heartbeat will show up in the brain waves of any weaker people in the group. In other words, you get entrained down to their level. This is one of the reasons at the end of the day you go home mentally tired. In summary All the above is very difficult to change in the world we live in today, we fly from one time zone to another, we have deadlines to meet, training is often done in the evening after work when we should really be winding down, your young child cries at night causing you to release cortisol again and so on. With that said, I would recommend that if you are unable to recover from injury, are suffering from lack of energy, get irritable quickly or just cannot sleep, then you take a look at your sleep pattern. Note.Some of the information in this thread was taken in part from Eat Move and Be Healthy by Paul Chek.