Promille thresholds, elimination, and why 'I feel okay' isn't enough
Alcohol, drugs and certain medicines reduce judgment, attention, coordination and reaction time. The danger starts long before the driver feels impaired. Alcohol lowers self-criticism, so the affected person often believes they're driving well while taking greater risks, scanning less and reacting more slowly. That's exactly why drunk driving is one of traffic's most serious threats.
Under Trafikbrottslagen §4, the limit for drunk driving is 0,2 promille in blood. At 1,0 promille it counts as gross drunk driving (§4a), with up to 2 years' prison as the normal sentence. Alcohol metabolises at roughly 0,15 promille per hour. After an evening at 1,0 promille it takes 5–6 hours to get back under the limit. Count in hours, not in 'I slept for a bit'.
You had dinner last night, drank 4 glasses of wine and stopped at 01:00. You're due to drive at 06:00. 4 glasses of wine ≈ 1,0 promille peak. By 06:00 (5 hours later) you're at 1,0 minus 5 × 0,15 = 0,25 promille — still over the 0,2 drunk-driving limit. Right choice: wait at least two more hours. Always count in hours, not in 'but I slept'.
A common exam trap is the belief that coffee, cold air, food or a shower can 'fix' alcohol impairment. They cannot. Only time lowers blood alcohol. Another common miss is thinking 'I feel normal, so I am normal'. Feeling unaffected isn't the same as being unaffected — alcohol lowers self-criticism first.