Sleep as much as needed to feel refreshed and healthy during the following day, but not more. Curtailing time in bed a bit seems to solidify sleep: excessively long times in bed seem related to fragmented and shallow sleep.

A regular arousal time in the morning seems to strengthen circadian cycling and to finally lead to regular times of sleep onset.

A steady daily amount of exercise probably deepens sleep over the long run, but occasional one-shot exercise does not directly influence sleep during the following night.

 Occasional loud noises (e.g., aircraft fly-overs) disturb sleep even in people who do not awaken because of the noises and cannot remember them in the morning. Sound-proofing the bedroom might be advisable for people who have to sleep close to excessive noise.

Although an excessively warm room disturbs sleep, there is no evidence that an excessively cold room solidifies sleep, as has been claimed.

 Hunger may disturb sleep. A light bedtime snack (especially warm milk or similar drink) seems to help many individuals sleep.

 An occasional sleeping pill may be of some benefit, but the chronic use of hypnotics is ineffective at most and detrimental in some insomniacs.

  Caffeine in the evening disturbs sleeps, even in persons who do not feel it does.

 Alcohol helps tense people to fall asleep fast, but the ensuing sleep is then fragmented.

Rather than trying harder and harder to fall asleep during a poor night, switching on the light and doing something else may help the individual who feels angry, frustrated, or tense about being unable to sleep.