So what are the effects of hypoxia?

Well, it depends what your altitude is and varies from person to person. The effects become progressively more profound the longer you are exposed to the altitude e.g. over an hour. Also exercising, cold or hot temperatures, medical illness, poor fitness, fatigue, panic, alcohol and a wide range of drugs will all aggravate the effects.

Conversely, gradual acclimatisation over several days and weeks (as seen in mountaineers) will improve your tolerance to the effects of hypoxia.

At the following altitude, you may experience:

Height: 1000m

Faculty Effect
Visual Skills unchanged
Memory unchanged
Reaction / Motor Skills unchanged
Personality Change unchanged
Perception unchanged

Height: 2000m

Faculty Effect
Visual Skills Night vision slightly impaired
Memory unchanged
Reaction / Motor Skills unchanged
Personality Change unchanged
Perception None, though exercise tolerance impaired

Height: 3000m

Faculty Effect
Visual Skills Night vision impaired
Memory Possible slight short term memory impairment
Reaction / Motor Skills Possible complex & unlearned choice reaction time slowing
Personality Change Possible change in personality in some
Perception None, exercise tolerance significantly impaired

Height: 4000m

Faculty Effect
Visual Skills Slight tunnelling of vision possible
Memory Some short term memory impairment
Reaction / Motor Skills Most complex choice reaction time slowed and errors increased
Personality Change Some emotional volatility, euphoria, loss of insight & judgement
Perception Frequently none. Sometimes feeling of happiness and contentment

Height: 5000m

Faculty Effect
Visual Skills Tunnelling of vision likely. Some loss of colour perception
Memory Significant short term memory impairment
Reaction / Motor Skills Generalised reaction time slowing and increase in errors
Personality Change Frequent personality change. Emotions insight and judgement profoundly affected
Perception Frequently none, but obvious to others. Feeling slightly drunk, happy, light-headed

Height: 6000m

Faculty Effect
Visual Skills Tunnelling of vision and more loss of colour perception
Memory Profound short term memory impairment
Reaction / Motor Skills Profound generalised reaction time slowing and error rate increase. Clumsy movements. Small chance of fits and loss of consciousness
Personality Change Frequent personality change. Volatility, judgement and insight impairment. Considerable disinhibition & loss of willpower
Perception Frequently none. Very obvious to others. Feeling drunk, unreal confused, uncoordinated “tingling pins & needles"

Height: 7000m

Faculty Effect
Visual Skills Loss of consciousness in approx 10 minutes
Memory Considerable confusion in approx 6 minutes
Reaction / Motor Skills Loss of consciousness in approx 10 minutes
Personality Change Loss of consciousness in approx 10 minutes
Perception Often none until consciousness lost. Otherwise as above

Height: 8000m

Faculty Effect
Visual Skills Loss of consciousness in approx 4 minutes
Memory Loss of consciousness in approx 4 minutes
Reaction / Motor Skills Considerable confusion in approx 2.5 minutes
Personality Change Loss of consciousness in approx 4 minutes
Perception Often none until consciousness lost. Otherwise as above

Height: 9000m

Faculty Effect
Visual Skills Loss of consciousness in approx 2.5 minutes
Memory Loss of consciousness in approx 2.5 minutes
Reaction / Motor Skills Considerable confusion in approx 1.5 minutes
Personality Change Loss of consciousness in approx 2.5 minutes
Perception Often none until consciousness lost. Otherwise as above

Height: 10,000m

Faculty Effect
Visual Skills Loss of consciousness in approx 1.5 minutes
Memory Loss of consciousness in approx 1.5 minutes
Reaction / Motor Skills Considerable confusion in approx 1 minute
Personality Change Loss of consciousness in approx 1.5 minutes
Perception Often none until consciousness lost. Otherwise as above