I have “sleep creep”. My body wants to stay up longer than my intended bedtime. My brain wants to sleep in longer than my intended wake-up time. When I give into my brain & body, go to bed and get up when I feel like it, pretty soon I am staying up late and getting up late.
I particularly don’t like my sleep creep because I love to be outside in the morning – especially in the California sunshine. (I grew up in Arizona where sunshine can be brutal.) I wondered why I can make myself stay awake but can’t MAKE myself fall asleep? I listened to a few podcasts on sleep that gave me more answers and tips to regulate my wake-sleep cycle and avoid “sleep creep”. Peggy
What makes us get sleepy? There are 2 main forces:
Sleep force 1 – Adenosine
The chemical adenosine is a molecule which creates a “desire” to sleep. Levels of it are very low when sleeping and build during the day – the longer we are awake the higher the adenosine levels and the sleepier we become.
Why Caffeine creates alertness
Caffeine acts like an adenosine antagonist—it binds to the adenosine receptor, so you get less adenosine and our “sleepy” signal is temporarily blocked. When caffeine wears off adenosine quickly binds to its receptors and we become sleepy.
Sleep force 2 – Circadian Rhythm
When morning comes we get an increase in energy, no matter how long we’ve slept or adenosine levels. This is because of the second force that governs wakefulness is our circadian clock. Our brain is “programmed” to wake up when the sun rises and adenosine is low. At this time a pulse of cortisol and epinephrine (adrenaline) are released which increases heart rate and muscle tension to make us feel awake.
To help set this cycle our brain neurons need light. Neurons respond best to sunrise light when the solar angle is low and the contrast between blue and yellow is highest.
Special retinal ganglion cells in the eye (not the cells we see with) register this type of light and communicates to our brain’s “clock” (the superchiasmatic nucleus) which connects to every body cell.
This clock sets our circadian rhythm, which times the release of cortisol and epinephrine in the morning, and sets a cellular timer for melatonin to be released later to help us fall asleep. If the circadian rhythm is not set early enough there can be negative effects for the cardiovascular system, metabolic system, mood, and learning .
Resetting Sleep Creep with Morning Light
- Get outside early, within an hour or two of sunrise to optimally time the cortisol pulse. Once the sun is overhead the opportunity to time your morning cortisol is gone.
- Don’t wear sunglasses to block the rays
- Even on a cloudy day, outside you will get 10,000 to 50,000 lux outside (inside it is only about 500), so this is why being outside is important.
- You need 2 to 10 minutes outside to set your internal clock, but as little as one minute may work if the light is bright.
Resetting Sleep Creep with Evening light
The sunset effect:
Early sun sets our clock and keeps it set but sunset also plays a part. When you view the sunset, melatonin signals your clock that it is the end of the day. Being outside within an hour or so of sunset prevents some of the negative effects of light later in the day so go outside for 2-10 minutes just before sunset.
The peak output of wakefulness and suppression of sleep happens late in day – about an hour before your bedtime you are most awake (some experience this as anxiety). The desire to be active in the evening lasts about 45 minutes. (If you are around children who are very active just before bedtime, don’t worry . . . for at least 45 minutes).
How to Use light to deliberately shift sleep cycle:
Our upper visual field contain the cells are that detect sunlight. At night it’s best to avoid exposing light to those cells.
- Place lights low. For example, use table lamps rather than overhead lighting.
- Keep the lights dim.
- The longer awake, the more light sensitive we are. Artificial or screen light can disrupt sleep-wake cycles so get as little light as possible after 8 pm.
- Light between 11 pm and 4 am will suppresses the release of dopamine which impacts mood and focus.
Does how long you sleep matter?
A recent finding that is both exciting and interesting comes from the Harvard Medical School lab of Dr. Robert Stickgold. His research shows that consistency of sleep duration is as important- possibly more important – as total sleep time for many forms of learning. (For example, it is better to get 5 hours every night, then sleeping 5 hours one night, 7 hours, 10 hours, 6 hours the next nights.)
Here’s one of the podcasts I listened to: