Why is it that sometimes when you sleep a short time seems like was long and other times all night only couple of minutes?

There are a few reasons why this happens:

Differences in sleep cycles: Sleep is divided into multiple cycles, each lasting about 90 minutes. Each cycle consists of four stages: N1, N2, N3 (deep sleep), and REM (rapid eye movement). The amount of time you spend in each stage varies throughout the night. If you wake up during a deep sleep stage (N3 or REM), you may feel groggy and disoriented, and time may seem to have passed more quickly. On the other hand, if you wake up during a lighter sleep stage (N1 or N2), you may feel more refreshed and alert, and time may seem to have passed more slowly.

Circadian rhythm: Your circadian rhythm, or internal body clock, plays a role in how you experience time. When your body is in sync with your circadian rhythm, you may feel more alert and energetic during the day and more tired and sleepy at night. When your circadian rhythm is disrupted, such as when you travel or work shift work, you may feel more tired and groggy, and time may seem to pass more slowly.

Age: As we get older, our sleep patterns change. We tend to get less deep sleep and more light sleep, which can make us feel like we've slept for a shorter amount of time than we actually have.

Medications and substances: Some medications and substances, such as alcohol and caffeine, can affect our sleep patterns and make us feel like we've slept for a different amount of time than we actually have.

Stress and anxiety: Stress and anxiety can also affect our sleep patterns and make us feel like we've slept for a different amount of time than we actually have.