1. Recommended Sleep Duration
- Newborns: Up to 17 hours per day.
- Adults: Up to 9 hours of uninterrupted sleep per day.
- Adults (65+ years): More than 7 hours per day.
Note: There are 4 stages of sleep (N1, N2, N3, and REM). These will be discussed in a later blog.
2. Sleep Regulation: The Two-Process Model
A. Homeostatic Process (Sleep Drive)
- The longer you are awake, the more "sleep pressure" (the desire to sleep) builds up.
- This process is mediated by a build-up of adenosine in the brain, which is cleared during sleep.
- Caffeine acts as an adenosine antagonist, which is why it keeps you awake.
B. Circadian Process (Internal Clock)
- This is the body's internal 24-hour clock, which is controlled by melatonin.
- Sunlight is the primary regulator of melatonin release. Morning light decreases melatonin production to promote alertness, preparing your body to wind down for sleep in the evening.
3. Other Neurotransmitters and Hormones in Sleep
A. Wake-Promoting Elements
- Examples include adrenaline and histamine.
- Note: Older-generation antihistamines block these signals, which causes drowsiness.
B. Sleep-Promoting Elements
- An example is GABA.
- Alcohol and benzodiazepines increase GABA activity, leading to sleepiness.
C. Hormonal Influence
- Growth Hormone: Released predominantly at night. Children with poor sleep quality (such as bad snorers) may experience growth retardation.
- Cortisol: Peaks just before waking to promote alertness.
- Thyroid Stimulating Hormone (TSH): Peaks during sleep.
- Leptin & Ghrelin:
- Leptin is released from fat cells and signals satiety (fullness). Sleep deprivation causes leptin resistance, which leads to increased eating, weight gain, and a vicious cycle of poor sleep.
- Ghrelin signals hunger. Sleep deprivation increases ghrelin production, which similarly increases weight and feeds into the disruptive sleep cycle.
4. Strategies for Managing Sleepiness and Regulating Sleep
- A. Napping: A brief 15-minute nap is excellent for decreasing accumulated adenosine, helping you feel refreshed without entering deep sleep.
- B. Light Therapy: Maximize exposure to natural sunlight during the day. In the evening, dim your lights and avoid blue light from digital devices. Using "yellow" or "warm" light bulbs is highly recommended.
- C. Melatonin Supplementation:
- A low dose taken five hours before sleep can assist with Delayed Sleep Phase Syndrome (to be discussed at a later stage).
- A higher dose can be used strictly as a sleep aid right before bed.
- D. Strict Sleep Schedule: Maintaining a consistent sleep schedule seven days a week will effectively stabilize your circadian rhythm.