有氧运动做得太晚，离bedtime太近，是会导致入睡困难。

举铁weight training 这样的无氧运动反而让人提前犯困，尤其是刚开始练的时候

网上看来的，

Some people may find that exercising close to bedtime seems to keep them up at night, says Gamaldo. How does working out affect the mind?

• Aerobic exercise causes the body to release endorphins. These chemicals can create a level of activity in the brain that keeps some people awake. These individuals should exercise at least 1 to 2 hours before going to bed, giving endorphin levels time to wash out and “the brain time to wind down,” she says.
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• Exercise also raises your core body temperature. “The effect of exercise in some people is like taking a hot shower that wakes you up in the morning,” says Gamaldo. Elevation in core body temperature signals the body clock that it’s time to be awake. After about 30 to 90 minutes, the core body temperature starts to fall. The decline helps to facilitate sleepiness.

睡前洗澡对我也有类似效果，本来已经晕乎乎困死了，一洗个热水澡，居然精神了，半小时一小时后才逐渐恢复睡意