L

Hours

Fig. 19.6 Normal hypnogram they feel or how pleased that it's not time to get up yet, with an immediate return to sleep. If during the short period of waking some factor causes anxiety or anger, e.g. aircraft noise, partner's snores or dread of being awake, progress to full awakening and being remembered is much more likely. The more times this happens the more subjects complain of an unrefreshing sleep. The time spent asleep as a percentage of the time in bed is used as a measure of sleep efficiency (96% in the case shown in Figure 19.6).

One of the most common ways in which insomnia develops is by 'clock watching'; subjects check the time on awakening, remember it and repeat this cycle many times during the night. Remembering the time of a transient awakening reinforces the subject's perception of sleeping poorly (periods of sleep in between are neglected) and also produces anger and frustration which in turn delay their return to sleep and may promote subsequent awakenings.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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