About TV and computer work before bed...I have read that the light levels from those devices may disrupt your melatonin levels. Certain wavelengths of light affect sleep rhythms.
An excerpt from Wikipedia alludes to this:
Light dependence
Production of melatonin by the pineal gland is inhibited by light to the
retina and permitted by darkness. Its onset each evening is called the dim-light melatonin onset (DLMO).
It is principally blue light, around 460 to 480
nm, that suppresses melatonin,
[36] proportional to the light intensity and length of exposure. Until recent history, humans in temperate climates were exposed to few hours of (blue) daylight in the winter; their fires gave predominantly yellow light. The
incandescent light bulb widely used in the twentieth century produced relatively little blue light.
[37] Wearing glasses that block blue light in the hours before bedtime may decrease melatonin loss. Kayumov
et al. showed that light containing only wavelengths greater than 530 nm does not suppress melatonin in bright-light conditions.
[38] Use of blue-blocking goggles the last hours before bedtime has also been advised for people who need to adjust to an earlier bedtime, as melatonin promotes sleepiness.
[39]
When used several hours before sleep according to the
phase response curve for melatonin in humans, small amounts (0.3 mg
[40]) of melatonin shift the circadian clock earlier, thus promoting earlier sleep onset and morning awakening.
[41]