So we know that sleep consists of two physiological states : 75% of rapid eye movement (REM) and 25% of nonrapid eye movement (NREM). It takes about 15-20 minutes to fall asleep. When we go to sleep, we will first experience NREM sleep, comprising of four stages. Stage I and Stage II occurs in the next 45 minutes. Stage II makes up 45% of our sleep. This is the time when you feel drowsy, and people can wake you up easily. But when it gets to Stage III and IV, this is the deep sleep. Largest stimulus is needed to arouse one in these stages. It is also the time when you experience sleepwalking or night terror. These stages last 45 minutes. After NREM, we will have REM sleep. We can say that average REM latency (from the time of sleep onset to REM onset) is 90 minutes. When we go into REM state, we DREAM.
The characteristics of REM sleep aka paradoxical sleep:
1. Rapid eye movements
3. Autonomic instability (increase heart rate, blood pressure and respiratory rate, increase variability of HR, BP and RR from minute to minute, appears similar to an awake person on EEG)
4. Tonic inhibition of skeletal muscle tone (paralysis)
5. Reduced in hypercapnic respiratory drive, no increase in tidal volume as partial pressure of carbon dioxide decreases
6. Relative poikilothermia (cold-bloodedness)
7. Penile tumescence or vaginal lubrication
8. Reduced sensistivity to sounds
So, throughout the night when we sleep, we will go through four stages of NREM sleep followed by REM sleep. However, as the night progresses, each REM period becomes longer, and stages III and IV disappear. Hence, further into the night, we will sleep more lightly and dream more. Here are some figures to help you understand further:
|You can see that initially a person will experience stages I-IV, then REM but as the night progresses, stage III and IV disappear. REM sleep becomes longer. Taken from this website.|
|Stages of sleep defined by brain wave patterns taken from this website.|
|Summary taken from this website.|
Now let's talk about SLEEP DISORDERS. It can be divided into primary (not caused by another mental disorder) and secondary (can be caused by major depressive disorder, panic disorder, schizophrenia etc. that lasts for at least 1 month).
Two main primary sleep disorders consist of DYSSOMNIAS (abnormalities in the quality, amount or timing of sleep) and PARASOMNIAS (unusual or undesirable phenomena during sleep or on the threshold of sleep).
Dyssomnias can be further divided into:
1. Primary insomnia (difficulty in initiating or maintaining sleep) MOST COMMON TYPE
2. Primary hypersomnia (excessive daytime sleepiness or excessive daytime sleep)
3. Narcolepsy (characterized by excessive daytime sleep attacks, brief muscle weakness, sleep paralysis, dreamlike experience during transition from wakefulness to sleep and vice versa with hallucination or illusion, short sleep latency)
4. Breathing-related sleep disorders (apneas, hypoapneas and oxygen desaturations)
5. Circadian rhythm sleep disorders (misalignment between desired and actual sleep periods divided into delayed sleep phase, jet lag, shift work and unspecified)
6. Dyssomnias not otherwise specified (periodic leg movement disorder aka nocturnal myoclonus, restless leg syndrome aka Ekbom syndrome, Kleine-Levin syndrome, menstruation-associated syndrome, insufficient sleep, sleep drunkenness, altitude insomnia)
Parasomnias can be further divided into:
1. Nightmare disorder
2. Sleep terror disorder
3. Sleepwalking disorder aka somnambulism
4. Parasomnia not otherwise specified (sleep bruxism aka tooth grinding, REM sleep behavior disorder, sleep talking aka somniloquy, rhythmic movement disorder aka jactatio capitis nocturna, sleep paralysis not associated with narcolepsy and others)
Let's say if a patient has sleep disorder, do you prescribe medication straightaway?
The answer is NO. Why?
Because, the first thing you have to advise patient is to practise SLEEP HYGIENE.
What is sleep hygiene? It is nonspecific measures to induce sleep.
You can advise patient to do these:
1. Arise at the same time daily
2. Limit daily in-bed time to the usual amount before the sleep disturbance
3. Discontinue CNS-acting drugs such as caffeine, nicotine, alcohol or stimulants
4. Avoid daytime naps, except when sleep chart shows they induce better night sleep
5. Establish physical fitness by means of a graded program of vigorous exercise early in day
6. Avoid evening stimulation, substitute radio or relaxed reading for television
7. Try very hot, 20-minute, body temperature-raising bath soaks near bedtime
8. Eat at regular times daily, avoid large meals near bedtime
9. Practice evening relaxation routines such as progressive muscle relaxation or meditation
10. Maintain comfortable sleeping conditions
Source: Kaplan and Sadock's Pocket Handbook of Clinical Psychiatry Fifth Edition
I think I have to start practising sleep hygiene myself. My bed is sooo comfortable that I feel like sleeping all day longg. Hahahha.
Okie dokie. Enough lecture on sleep, now I have to go to bedd. But the problem is, now I don't feel like sleeping, because I just woke up from a 2-hour sleep! I have no one to blame but myself. Grr.
I'll watch a movie then! Oh oh have you seen How to Train Your Dragon 2? The movie is awesome, rightt! I wish I can have my own pet dragon, a cute and fluffy one, a PINK one!
And and have you watched The Expendables 3? Side Effects? Teenage Mutant Ninja Turtles? The Maze Runner? The Guardians of the Galaxy?
I am soo going to practise sleep hygiene after this LOL
You...have a good night sleep! And regulate your sleeping pattern okehh :D