But where unbruisèd youth with unstuffed brain
Doth couch his limbs, there golden sleep doth reign."

Shakespeare describes, too, with lifelike fidelity, the causes of
insomnia, which are not weariness or physical pain, but undue mental
anxiety. He constantly contrasts the troubled sleep of those burdened
with anxieties and cares, with the happy lot of the laborer whose
physical weariness insures him a tranquil night's repose. Henry VI.
says:--

"And to conclude, the shepherd's homely curds,
His cold thin drink out of his leather bottle,
His wonted sleep under a fresh tree's shade,
All which secure and sweetly he enjoys,
Are far beyond a prince's delicates."

And Henry V. says:--

"'Tis not the balm, the sceptre and the ball,
The sword, the mace, the crown imperial,
The intertissued robe of gold and pearl,
The farcèd title running 'fore the king,
The throne he sits on, nor the tide of pomp
That beats upon the high shore of this world,--
No, not all these, thrice gorgeous ceremony,
Not all these, laid in bed majestical,
Can sleep so soundly as the wretched slave,
Who, with a body filled and vacant mind,
Gets him to rest, crammed with distressful bread;
Never sees horrid night, that child of hell,