Not to be able to sleep can be one of the most debilitating conditions. It leaves you worn out and unable to cope with life. Matthew Walker’s book, “Why we Sleep” gives insight into insomnia. He explains what might accidentally be spoiling our chances of a good night’s sleep. He describes your Chronotype. Are you an OWL or a LARK?
5 Factors that prevent sleep
- Constant electric light or screen glare from computers
- Regularised body temperature
- Caffeine from coffee tea and chocolate (especially dark chocolate)
- Alcohol consumption
- Work demands (stress at work)
Artificial light halts the biological clock of melatonin/adenosine. Most people have heard of melatonin. Few have heard of adenosine. The sleep-wake balance is regulated by adenosine (although it is probably not the only one). To achieve homeostasis (an internal system that helps stabilise body temperature, acidity etc) the neurotransmitter adenosine blocks body processes that promote wakefulness. The big focus is on those involving the neurotransmitters adrenaline, noradrenaline and serotonin.
SWITCH OFF! 2 – 3 hours of artificial light every evening can trigger sleep onset insomnia. All you have to do to stop this is to SWITCH OFF THE LIGHT. Artificial light stops rising melatonin levels in the blood. Even low level lighting can have this effect. Blue LED light is the worst culprit. It gets to the light receptors in the eyes that communicate “daytime”! It has twice the harmful impact on melatonin suppression. Just two hours on your laptop before bedtime can reduce melatonin production by 23%. Reading on an iPad reduces melatonin by up to 50%.
Caffeine mutes adenosine. Caffeine (from coffee, dark chocolate and tea) battles with adenosine for adenosine receptor sites by blocking the receptors and circumventing the sleep signals. Caffeine is a drug that tricks your brain into making you feel alert and wide awake. A caffeine ‘hit’ peaks after 30 minutes but it takes ages to clear out the caffeine from your body. Caffeine has a half life of about 5 to 7 hours, so it takes about 10 to 14 hours before your body is caffeine free. According to Professor Matthew Walker, it is one of the most common culprits stopping people from sleeping, therefore masquerading as insomnia. The P450 cytochrome 1A2 clears the liver of caffeine. When the liver does finally clear the caffeine, the body can experience a caffeine crash. That’s the result of an adenosine build up – the adenosine finally latches on to all the receptors the caffeine has vacated, giving an enormous urge to sleep.
After a good night’s sleep, levels of adenosine will be low. Your personal circadian rhythm will influence your wakefulness making you feel alert and wide awake at the appropriate time. If you awake feeling groggy, your levels of caffeine may still be blocking adenosine receptors giving you that groggy morning feeling. The response – people start the vicious cycle over again by having another cup of coffee! Over a long period this can manifest as sleep deprivation.
Body temperature is also a sleep regulator. Body temperature rises during the day and drops at bedtime/night time. It reaches its lowest about two hours after sleep onset. It does this whether you are awake or in deep sleep. This demonstrates that the sleep/wake patterns are massively influenced by circadian rhythm. Some people are ‘early birds’ and some are ‘night owls’. It’s very important to respect whichever one you are because this is your CHRONOTYPE. Your DNA dictates which one you are. If you are an owl, your body temperature will drop hours after the early bird’s. Your cycle will trend towards ‘late to bed late to rise’ meaning for you an early start is not synchronising with your natural circadian rhythm.
I AM AN OWL! Sadly human behaviour does not favour owls! The pace of life it is stacked agains owls who are happy being awake until well after midnight. This means they need to sleep in beyond the wake-up of most people. Working against your chronotype does little to help when you have to be up and busy at 7.00am. Ideally for you, staying asleep until 10.00am is better suited to your DNA sleep profile. Establishing your chronotype can help you sleep better.
Melatonin regulates the TIMING of sleep but not the GENERATION of sleep. It is not a sleeping aid but more a sleeping placebo. Melatonin production declines across the night and into the morning. Dawn or bright lights switches off the production.
The circadian rhythm, your chronotype and sleep pressure determine your wake/sleep pattern. Finding out what suits you, avoiding the stimulants (caffeine, bright lights, alcohol) that block the adenosine receptors is a good place to start. You can re-establish your poor sleeping patterns into healthy ones.