As we learn more about sleep, it becomes obvious that this is a vital time to ‘reset’ your mental and physical health. It is easy to be fooled into believing that sleeping is a very passive event. The truth is, that our brainwave activity is more pronounced during some stages of sleep than when we are awake.
From an evolutionary standpoint, it defies common sense that we have evolved to a point where we need to sleep for 7-9 hours a day. During this time, we are not hunting, gathering or looking after our young. We are also very vulnerable to predation when we are asleep. There must be very good reason, for mother nature to ‘shut us down’ each day. As we learn more about sleep, it becomes obvious that this is a vital time to ‘reset’ your mental and physical health. It is easy to be fooled into believing that sleeping is a very passive event. The truth is, that our brainwave activity is more pronounced during some stages of sleep than when we are awake.
General advice specifies that we should be getting about 7-9 hours sleep a day. This means that we are awake for 15-17 hours. Our natural internal clock does not keep exact time. In fact, on average, it lags about 30 minutes a day. Environmental cues help us stay on time by resetting our clocks each day. Sunlight is the best reference point for our system to use to calibrate. Melatonin is a chemical, which communicates to the system when it is daytime v night-time, and when it is time to go to sleep. Light in the eyes inhibits melatonin. As dusk begins to rise, inhibition is reduced, and melatonin levels increase. It rises and peaks around the time we go to sleep.
Another important chemical involved in sleep regulation is adenosine. From the moment you wake up, adenosine is building up in our brain. The longer that we are awake, the more that it builds up. Adenosine is built up as neurons work and with robust energy, adenosine is a by-product that is produced. The more it builds up, the sleeper we get and sleep pressure increases. Adenosine works by dialling up the receptors that promote sleepiness and dialling down the receptors which stimulate wakefulness. Serotonin is also in higher levels in our brain during wakefulness and slowly reduces during the first stages of sleep. As you enter a sleep stage call REM, serotonin is shut off.
Our environment therefore helps determine our sleep patterns and periods of wakefulness. In addition to light, temperature, food timing and our daily routines can also help our system develop these regular rhythms. In order to develop consistent sleep patterns, we should aim to get light in your eyes in the early part of the day and at for least 30-40 minutes throughout the day. This becomes an important cue, which helps regulate melatonin levels. In a natural environment, melatonin would increase as the light goes down at the end of the day. We can prevent this natural process by operating in artificial light after the sun goes down.
Temperature is an important element in sleep. Typically, as the sun goes down, temperature also reduces. We drop by 1 degree in temperature when we sleep, so it is easier to go to sleep in a colder room than a hotter one. Both exercise and activity are great cues for circadian rhythm alignment. Being active during the day, both brain and body will promote increased adenosine levels so that we will feel sleepy by the end of the day. Usually, we begin to slow down our activity towards the end of the day, which is another cue for your system that we are winding down. Regular mealtimes and the choosing foods that meet the needs for the time of day are also important reference points for your system.
By understanding the role of these natural chemicals and the affect they have on our sleep, we can become better aware of how our environment influences our sleep patterns. Some simple tips based on this understanding would be:
- Light
- Promote: We should aim to get light in your eyes in the early part of the day and at for least 30-40 minutes throughout the day
- Avoid: As the natural light goes down at the end of the day, aim to avoid artificial light before the hours of sleep.
- Temperature:
- Promote: Sleep in a cool room. About 18 degrees has been shown to be a good temperature to optimise a good sleep.
- Avoid: Being hot or cold will affect your sleep patterns.
- Activity (Brain & Body)
- Promote: Aim to be active during the day. This can be planned activity like exercise, and / or, being generally active during activities of daily living. Our thoughts and emotions also stimulate neural activity, which lead to the accumulation of adenosine throughout the day. Ultimately, it this build-up of adenosine that signals to our system that we need to go to sleep.
- Avoid: Being inactive or idol during the day will do little to promote the feeling of sleepiness by the end of the day. In addition, ramping up activity (mental or physical) before you aim to go to sleep, might also disrupt the cues for sleep. Typically, we should be slowing down before we go to sleep.
- Food / Drink:
- Promote: Regular mealtimes help develop consistent patterns of behaviour. If you eat at similar times each day, the system will begin to regulate activity and functions around these predictable times, including sleep.
- Avoid: Some foods and drinks should be avoided to prevent disruptions in those natural sleep chemicals. Caffeine blocks the receptors for adenosine, which reduces sleepiness. Alcohol is a sedative, but not a sleep aid. When you have a drink, your cortex is put under sedation, so it might feel like you are falling asleep easier, but it is losing consciousness easier (not going to sleep easier). Alcohol, via the activation of the SNS will lead you to wake more often, thereby creating a more fractured sleep.